Increasing gaps between consecutive Niven numbers: Difference between revisions
Increasing gaps between consecutive Niven numbers (view source)
Revision as of 10:30, 25 January 2021
, 3 years agoAdd Fortran
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27 153 179,838,772 2,998,895,823</pre>
=={{header|Fortran}}==
{{trans|C}}
<lang Fortran> program nivengaps
implicit none
integer*8 prev /1/, gap /0/, sum /0/
integer*8 nividx /0/, niven /1/
integer gapidx /1/
character*13 idxfmt
character*14 nivfmt
write (*,*) 'Gap no Gap Niven index Niven number '
write (*,*) '------ --- ------------- --------------'
10 call divsum(niven, sum)
if (mod(niven, sum) .EQ. 0) then
if (niven .GT. prev + gap) then
gap = niven - prev
call fmtint(nividx,13,idxfmt)
call fmtint(prev,14,nivfmt)
write (*,20) gapidx,gap,idxfmt,nivfmt
gapidx = gapidx + 1
end if
prev = niven
nividx = nividx + 1
end if
niven = niven + 1
if (gapidx .LE. 32) go to 10
stop
20 format (i7,' ',i3,' ',a13,' ',a14)
end program
C Sum of divisors of NN, given the sum of divisors of NN-1
subroutine divsum(nn,sum)
implicit none
integer*8 n,nn,sum
n = nn
sum = sum + 1
30 if (n.GT.0 .AND. mod(n,10).EQ.0) then
sum = sum - 9
n = n / 10
go to 30
end if
end subroutine
integer*8 function mod(a,b)
implicit none
integer*8 a,b
mod = a - a/b * b
end function
C Format a positive integer with ',' as the thousands separator.
subroutine fmtint(num, len, str)
implicit none
integer*8 n, num
integer pos, len, th
character(*) str
n=num
pos=len
th=2
40 if (pos.GT.0) then
if (n.EQ.0) then
str(pos:pos) = ' '
else
str(pos:pos) = achar(mod(n,10) + iachar('0'))
if (th.EQ.0 .AND. n.GE.10 .AND. pos.GT.1) then
th = 2
pos = pos-1
str(pos:pos) = ','
else
th = th-1
end if
end if
pos = pos - 1
n = n/10
go to 40
end if
end subroutine</lang>
{{out}}
<pre> Gap no Gap Niven index Niven number
------ --- ------------- --------------
1 1 1 1
2 2 10 10
3 6 11 12
4 7 26 63
5 8 28 72
6 10 32 90
7 12 83 288
8 14 102 378
9 18 143 558
10 23 561 2,889
11 32 716 3,784
12 36 1,118 6,480
13 44 2,948 19,872
14 45 4,194 28,971
15 54 5,439 38,772
16 60 33,494 297,864
17 66 51,544 478,764
18 72 61,588 589,860
19 88 94,748 989,867
20 90 265,336 2,879,865
21 99 800,054 9,898,956
22 108 3,750,017 49,989,744
23 126 6,292,149 88,996,914
24 135 44,194,186 689,988,915
25 144 55,065,654 879,987,906
26 150 61,074,615 989,888,823
27 153 179,838,772 2,998,895,823
28 192 399,977,785 6,998,899,824
29 201 497,993,710 8,889,999,624
30 234 502,602,764 8,988,988,866
31 258 547,594,831 9,879,997,824
32 276 1,039,028,518 18,879,988,824</pre>
=={{header|Go}}==
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