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 A143151 #10 May 07 2025 08:26:27 %S A143151 1,1,2,1,0,3,1,2,0,2,1,0,0,0,5,1,2,3,0,0,2,1,0,0,0,0,0,7,1,2,0,2,0,0, %T A143151 0,2,1,0,3,0,0,0,0,0,3,1,2,0,0,5,0,0,0,0,2,1,0,0,0,0,0,0,0,0,0,11,1,2, %U A143151 3,2,0,2,0,0,0,0,0,2,1,0,0,0,0,0,0,0,0,0,0,0,13,1,2,0,0,0,0,7,0,0,0,0,0,0,2 %N A143151 Triangle read by rows, A051731 * (A020639 * 0^(n-k)), 1<=k<=n. %C A143151 Row sums = A143152: (1, 3, 4, 5, 6, 8, 8, 7, 7, 10, 12, 12, 14, 12, ...). %F A143151 Triangle read by rows, A051731 * (A020639 * 0^(n-k)), 1<=k<=n; where A020639 = Lpf(n). By rows, least prime factors of the divisors of n, where the divisors of n are recorded in triangle A127093. %e A143151 First few rows of the triangle are: %e A143151 1; %e A143151 1, 2; %e A143151 1, 0, 3; %e A143151 1, 2, 0, 2; %e A143151 1, 0, 0, 0, 5; %e A143151 1, 2, 3, 0, 0, 2; %e A143151 1, 0, 0, 0, 0, 0, 7; %e A143151 1, 2, 0, 2, 0, 0, 0, 2; %e A143151 1, 0, 3, 0, 0, 0, 0, 0, 3; %e A143151 1, 2, 0, 0, 5, 0, 0, 0, 0, 2; %e A143151 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 11; %e A143151 ... %e A143151 Row 12 = (1, 2, 3, 2, 0, 2, 0, 0, 0, 0, 0, 2) since the divisors of 12 are shown in row 12 of triangle A127093: (1, 2, 3, 4, 0, 6, 0, 0, 0, 0, 0, 12). %e A143151 Lpf of these terms = row 12 of A143152. %Y A143151 Cf. A020639, A127093, A143152. %K A143151 nonn,tabl %O A143151 1,3 %A A143151 _Gary W. Adamson_ and _Mats Granvik_, Jul 27 2008