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 A276682 #10 Dec 02 2024 18:09:16 %S A276682 1,3,8,4,6,4,8,12,6,6,18,8,4,8,16,8,8,9,14,24,8,4,16,12,8,8,24,8,12, %T A276682 12,8,20,8,4,48,24,4,12,16,24,8,12,12,16,18,4,20,16,9,16,40,8,8,8,24, %U A276682 36,8,4,24,24,4,16,24,12,24,8,16,16,8,12,16,18,8,16 %N A276682 Number of divisors of the n-th 9-gonal number. %H A276682 Colin Barker, <a href="/A276682/b276682.txt">Table of n, a(n) for n = 1..1000</a> %F A276682 a(n) = A000005(A001106(n)). %e A276682 a(2) = 3 because the 2nd 9-gonal number is 9, which has 3 divisors: 1,3,9. %t A276682 DivisorSigma[0,PolygonalNumber[9,Range[80]]] (* _Harvey P. Dale_, Dec 02 2024 *) %o A276682 (PARI) %o A276682 pg(m, n) = (n^2*(m-2)-n*(m-4))/2 \\ n-th m-gonal number %o A276682 vector(150, n, numdiv(pg(9,n))) %Y A276682 Cf. A000005, A001106. %Y A276682 Cf. A063440 (m=3), A048691 (m=4), A276678 (m=5), A276679 (m=6), A276680 (m=7), A276681 (m=8), A276683 (m=10). %K A276682 nonn %O A276682 1,2 %A A276682 _Colin Barker_, Sep 13 2016