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 A092371 #17 Jan 04 2025 12:00:46 %S A092371 1,6,1,18,15,1,40,90,28,1,75,350,280,45,1,126,1050,1680,675,66,1,196, %T A092371 2646,7350,5775,1386,91,1,288,5880,25872,34650,16016,2548,120,1,405, %U A092371 11880,77616,162162,126126,38220,4320,153,1,550,22275,205920,630630 %N A092371 Triangle read by rows: T(n, k) = binomial(n, k) * binomial(n+k, n-k). %C A092371 Related to the coefficients of x^k y^k in the n-th power of x^2 + x*y + 2*x + y + 1. - _F. Chapoton_, Jan 04 2025 %F A092371 T(n, k) = [x^(n-k)] F(-n, -n-k; 1; x). - _Paul Barry_, Sep 04 2008 %e A092371 Triangle starts: %e A092371 [1] 1; %e A092371 [2] 6, 1; %e A092371 [3] 18, 15, 1; %e A092371 [4] 40, 90, 28, 1; %e A092371 [5] 75, 350, 280, 45, 1; %e A092371 [6] 126, 1050, 1680, 675, 66, 1; %e A092371 [7] 196, 2646, 7350, 5775, 1386, 91, 1; %e A092371 [8] 288, 5880, 25872, 34650, 16016, 2548, 120, 1; %p A092371 T := (n, k) -> binomial(n, k) * binomial(n+k, n-k): # _Peter Luschny_, Jan 04 2025 %o A092371 (PARI) T(n,k) = binomial(n,k)*binomial(n+k,n-k) %Y A092371 First column = A002411, second column = A001297, third column = A107418, fourth column = A105251, fifth column = A104673. %Y A092371 Main diagonal = 1, second diagonal = A000384. %Y A092371 Cf. A063007, A006480 (central terms), A082759 (row sums + 1). %Y A092371 Cf. A104684. %K A092371 nonn,tabl %O A092371 1,2 %A A092371 _Benoit Cloitre_, Mar 20 2004