Pernicious numbers: Difference between revisions
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888888877 888888878 888888880 888888883 888888885 888888886
</pre>
=={{header|Ksh}}==
<lang ksh>
#!/bin/ksh
# Positive integer whose population count is a prime
# # Variables:
#
integer PNUM=25 MINN=888888877 MAXN=888888888
# # Functions:
#
# # Function _dec2bin(n) - return binary representation of decimal n
#
function _dec2bin {
typeset _n ; integer _n=$1
typeset _base ; integer _base=2
typeset _q _r _buff ; integer _q _r
typeset -a _arr _barr
(( _q = _n / _base ))
(( _r = _n % _base ))
_arr+=( ${_r} )
until (( _q == 0 )); do
_n=${_q}
(( _q = _n / _base ))
(( _r = _n % _base ))
_arr+=( ${_r} )
done
_revarr _arr _barr
_buff=${_barr[@]}
echo ${_buff// /}
}
# # Function _revarr(arr, barr) - reverse arr into barr
#
function _revarr {
typeset _arr ; nameref _arr="$1"
typeset _barr ; nameref _barr="$2"
typeset _i ; integer _i
for ((_i=${#_arr[*]}-1; _i>=0; _i--)); do
_barr+=( ${_arr[_i]} )
done
}
# # Function _isprime(n) return 1 for prime, 0 for not prime
#
function _isprime {
typeset _n ; integer _n=$1
typeset _i ; integer _i
(( _n < 2 )) && return 0
for (( _i=2 ; _i*_i<=_n ; _i++ )); do
(( ! ( _n % _i ) )) && return 0
done
return 1
}
# # Function _sumdigits(n) return sum of n's digits
#
function _sumdigits {
typeset _n ; _n=$1
typeset _i _sum ; integer _i _sum=0
for ((_i=0; _i<${#_n}; _i++)); do
(( _sum+=${_n:${_i}:1} ))
done
echo ${_sum}
}
######
# main #
######
integer i sbi n=3 cnt=0
printf "First $PNUM Pernicious numbers:\n"
for ((n = cnt = 0; cnt < PNUM; n++)); do
bi=$(_dec2bin ${n}) # $n as Binary
sbi=${bi//0/} # Strip zeros (i.e. count ones)
_isprime ${#sbi} # One count prime?
(( $? )) && { printf "%4d " ${n} ; ((++cnt)) }
done
printf "\n\nPernicious numbers between %11,d and %11,d inclusive:\n" $MINN $MAXN
for ((i=MINN; i<=MAXN; i++)); do
bi=$(_dec2bin ${i})
sbi=${bi//0/}
_isprime ${#sbi}
(( $? )) && printf "%12,d " ${i}
done
echo
</lang>
{{out}}<pre>
First 25 Pernicious numbers:
3 5 6 7 9 10 11 12 13 14 17 18 19 20 21 22 24 25 26 28 31 33 34 35 36
Pernicious numbers between 888,888,877 and 888,888,888 inclusive:
888,888,877 888,888,878 888,888,880 888,888,883 888,888,885 888,888,886
</pre>
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