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 A038247 #9 Jul 08 2025 22:12:43
%S A038247 1,5,5,25,50,25,125,375,375,125,625,2500,3750,2500,625,3125,15625,
%T A038247 31250,31250,15625,3125,15625,93750,234375,312500,234375,93750,15625,
%U A038247 78125,546875,1640625,2734375,2734375,1640625,546875,78125
%N A038247 Triangle whose (i,j)-th entry is binomial(i,j)*5^(i-j)*5^j.
%D A038247 B. N. Cyvin et al., Isomer enumeration of unbranched catacondensed polygonal systems with pentagons and heptagons, Match, No. 34 (Oct 1996), pp. 109-121.
%t A038247 Table[Binomial[i,j]5^(i-j) 5^j,{i,0,10},{j,0,i}]//Flatten (* _Harvey P. Dale_, May 01 2022 *)
%K A038247 nonn,tabl,easy
%O A038247 0,2
%A A038247 _N. J. A. Sloane_