Magic constant: Difference between revisions

==={{header|FreeBASIC}}===

<lang freebasic>

function a(byval n as uinteger) as ulongint

n+=2

return n*(n^2 + 1)/2

end function

function inv_a(x as double) as ulongint

dim as ulongint k = 0

while k*(k^2+1)/2+2 < x

k+=1

wend

return k

end function

dim as ulongint n

print "The first 20 magic constants are ":

for n = 1 to 20

print a(n);" ";

next n

print

print "The 1,000th magic constant is ";a(1000)

for e as uinteger = 1 to 20

print using "10^##: #########";e;inv_a(10^cast(double,e))

next e</lang>

{{out}}<pre>

The first 20 magic constants are

15 34 65 111 175 260 369 505 671 870 1105 1379 1695 2056 2465 2925 3439 4010 4641 5335

The 1,000th magic constant is 503006505

10^ 1: 3

10^ 2: 6

10^ 3: 13

10^ 4: 28

10^ 5: 59

10^ 6: 126

10^ 7: 272

10^ 8: 585

10^ 9: 1260

10^10: 2715

10^11: 5849

10^12: 12600

10^13: 27145

10^14: 58481

10^15: 125993

10^16: 271442

10^17: 584804

10^18: 1259922

10^19: 2714418

10^20: 5848036

</pre>