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 A085767 #9 Feb 03 2015 19:21:57 %S A085767 1,3,3,3,2,3,5,11,9,7,4,3,9,7,12,11,6,27,13,27,12,4,8,27,17,35,27,19, %T A085767 10,12,21,43,15,23,5,27,25,19,9,27,14,12,29,11,27,8,16,75,33,67,6,35, %U A085767 18,27,15,75,51,39,20,27,41,31,54,43,22,15,45,40,54,7,24,27,49,99,42,19,26,39 %N A085767 Smallest m such that n divides the pentagonal number A000326(m). %H A085767 Harvey P. Dale, <a href="/A085767/b085767.txt">Table of n, a(n) for n = 1..1000</a> %e A085767 Let pe(m)=m*(3m-1)/2. The pe(1)=1, pe(2)=5, pe(3)=12. As pe(3) is the first divisible by 6, a(6)=3. %t A085767 smn[n_]:=Module[{m=1,c},c=(m(3m-1))/2;While[!Divisible[c,n],m++;c=(m(3m-1))/2];m]; Array[smn, 80] (* _Harvey P. Dale_, Feb 03 2015 *) %o A085767 (PARI) pe(n)=n*(3*n-1)/2 for (n=1,50,c=1; while (pe(c)%n!=0,c++); print1(c",")) %Y A085767 Cf. A011772 (triangular numbers), A019554 (squares). %K A085767 nonn %O A085767 1,2 %A A085767 _Jon Perry_, Jul 22 2003 %E A085767 More terms from _David Wasserman_, Feb 10 2005