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 A038273 #7 Jul 08 2025 22:15:16 %S A038273 1,7,7,49,98,49,343,1029,1029,343,2401,9604,14406,9604,2401,16807, %T A038273 84035,168070,168070,84035,16807,117649,705894,1764735,2352980, %U A038273 1764735,705894,117649,823543,5764801,17294403,28824005,28824005 %N A038273 Triangle whose (i,j)-th entry is binomial(i,j)*7^(i-j)*7^j. %D A038273 B. N. Cyvin et al., Isomer enumeration of unbranched catacondensed polygonal systems with pentagons and heptagons, Match, No. 34 (Oct 1996), pp. 109-121. %K A038273 nonn,tabl,easy %O A038273 0,2 %A A038273 _N. J. A. Sloane_