This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A196547 #6 Mar 30 2012 18:35:59 %S A196547 1,9,14,15,21,22,25,27,28,30,33,35,38,39,45,46,49,51,52,55,57,62,63, %T A196547 65,66,69,70,75,77,78,81,85,86,87,91,92,93,94,95,98,99,102,105,111, %U A196547 115,116,117,118,119,121,123,124,125,129,132,133,134,135,138,141,142 %N A196547 Nonprime numbers m such that the sum of the distinct residues of x^m (mod m) is divisible by m, x=0..m-1. %C A196547 Subset of A196546. %e A196547 a(3) = 14 because x^14 == 0, 1, 2, 4, 7, 8, 9, 11 %e A196547 (mod 14), and the sum 0+1+2+4+7+8+9+11 = 42 is divisible by 14. %p A196547 with(numtheory):T:=array(1..150): for n from 1 to 150 do:for k from 1 to n do:T[k]:=irem(k^n,n):od:W:=convert(T,set):x:=nops(W):s:=0:for i from 1 to x do:s:=s+W[i]:od:if irem(s,n)=0 and type(n,prime)=false then printf(`%d, `,n):else fi:od: %Y A196547 Cf. A195637, A196546. %K A196547 nonn %O A196547 1,2 %A A196547 _Michel Lagneau_, Oct 03 2011