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 A276681 #8 Sep 14 2016 05:59:55 %S A276681 1,4,4,8,4,12,4,10,9,16,4,16,4,20,8,12,6,24,8,16,8,16,4,40,6,16,8,16, %T A276681 8,40,8,14,8,24,8,24,4,24,16,20,6,32,4,32,24,20,4,24,12,24,8,32,4,56, %U A276681 8,20,12,16,12,32,4,20,24,32,8,48,4,16,16,48,4,30,8 %N A276681 Number of divisors of the n-th octagonal number. %H A276681 Colin Barker, <a href="/A276681/b276681.txt">Table of n, a(n) for n = 1..1000</a> %F A276681 a(n) = A000005(A000567(n)). %e A276681 a(4) = 8 because the 4th octagonal number is 40, which has 8 divisors: 1,2,4,5,8,10,20,40. %o A276681 (PARI) %o A276681 pg(m, n) = (n^2*(m-2)-n*(m-4))/2 \\ n-th m-gonal number %o A276681 vector(150, n, numdiv(pg(8,n))) %Y A276681 Cf. A000005, A000567. %Y A276681 Cf. A063440 (m=3), A048691 (m=4), A276678 (m=5), A276679 (m=6), A276680 (m=7), A276682 (m=9), A276683 (m=10). %K A276681 nonn %O A276681 1,2 %A A276681 _Colin Barker_, Sep 13 2016