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 A386549 #8 Jul 27 2025 11:16:21 %S A386549 0,1,72,7031,688942,67509261,6615218612,648223914691,63519328421082, %T A386549 6224245961351321,609912584884008352,59765209072671467151, %U A386549 5856380576536919772422,573865531291545466230181,56232965685994918770785292,5510256771696210494070728411,539948930660542633500160598962 %N A386549 Indices of hexagonal numbers that are one-sixth of another hexagonal number. %H A386549 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (99,-99,1). %F A386549 G.f.: x^2 * (1 - 27*x + 2*x^2) / (1 - 99*x + 99*x^2 - x^3). - _Jinyuan Wang_, Jul 26 2025 %e A386549 72 is in this sequence because the 72th hexagonal number (10296) is one-sixth of another hexagonal number. %Y A386549 Cf. A000384, A385917, A386550. %K A386549 nonn,easy %O A386549 1,3 %A A386549 _Kelvin Voskuijl_, Jul 25 2025 %E A386549 More terms from _Jinyuan Wang_, Jul 26 2025