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 A160991 #3 Sep 08 2022 08:45:45 %S A160991 1,3,15,25,42,74,96,126,156,177,268,393,293,527,573,732,623,772,887, %T A160991 903,1029,1010,1333,1398,1353,1594,2104,1786,1923,1971,2847,2744,2560, %U A160991 2282,3128,3133,2850,3634,3795,2976,4212,4092,4413,4596,4605,4679,6177,5158 %N A160991 Row sums of triangle defined in A112593. %e A160991 Fifth row is 7, 5, 5, 5, 0, 5, 5, 5, 5, so a(5) = 42. %o A160991 (Magma) S:=[[1]]; for i in [2..48] do Append(~S, [ &+[ Gcd(S[i-1][k], j) eq 1 select 1 else 0: k in [1..2*i-3] ]: j in [1..2*i-1] ]); end for; [ &+R: R in S ]; %Y A160991 Cf. A112593. %K A160991 nonn %O A160991 1,2 %A A160991 _Klaus Brockhaus_, Jun 01 2009