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 A272266 #9 Apr 24 2016 08:32:14 %S A272266 1,4,9,10,16,25,27,36,49,52,64,81,85,100,121,126,144,169,175,196,225, %T A272266 232,256,289,297,324,361,370,400,441,451,484,529,540,576,625,637,676, %U A272266 729,742,784,841,855,900,961,976,1024,1089,1105,1156,1225,1242,1296 %N A272266 The union of squares (A000290) and 10-gonal numbers (A001107). %H A272266 Colin Barker, <a href="/A272266/b272266.txt">Table of n, a(n) for n = 1..1000</a> %F A272266 Conjectures: %F A272266 a(n) = a(n-1)+2*a(n-3)-2*a(n-4)-a(n-6)+a(n-7) for n>7. %F A272266 G.f. x*(1+3*x+5*x^2-x^3-x^5+x^6) / ((1-x)^3*(1+x+x^2)^2). %o A272266 (PARI) %o A272266 pg(m, n) = (n^2*(m-2)-n*(m-4))/2 \\ The n-th m-gonal number %o A272266 pgr(m, r) = n=1; L=List(); while((t=pg(m, n))<r, listput(L, t); n++); Vec(L) %o A272266 pgpgs(p, q, r) = setunion(pgr(p, r), pgr(q, r)) %o A272266 pgpgs(4, 10, 2000) %Y A272266 Cf. A000290, A001107, A272267. %K A272266 nonn %O A272266 1,2 %A A272266 _Colin Barker_, Apr 24 2016