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 A385577 #7 Jul 07 2025 00:41:46 %S A385577 0,1,0,3,2,0,6,8,6,0,10,20,30,24,0,15,40,90,144,120,0,21,70,210,504, %T A385577 840,720,0,28,112,420,1344,3360,5760,5040,0,36,168,756,3024,10080, %U A385577 25920,45360,40320,0,45,240,1260,6048,25200,86400,226800,403200,362880,0 %N A385577 Array read by ascending antidiagonals: A(n,m) = n*Pochhammer(n+1,m+1)/(m+2). %D A385577 James J. Tattersall, Elementary Number Theory in Nine Chapters, Cambridge University Press, 1999, page 20. %H A385577 Paul W. Haggard and Bonnie L. Sadler, <a href="https://doi.org/10.1080/0020739940250205">A Generalization of Triangular Numbers</a>, International Journal of Mathematical Education in Science and Technology 25 (2): 195-202, (1994). %F A385577 Sum_{m=0..n} A(n-m,m) = A006231(n+1). %F A385577 A(n,1) = A007290(n+2). %F A385577 A(1,n) = A000142(n+1). %F A385577 A(2,n) = A001048(n+2). %F A385577 A(3,n) = abs(A238474(n+1)). %F A385577 A(n,n) = n!*A002740(n+2) %e A385577 Array begins as: %e A385577 0, 0, 0, 0, 0, 0, 0, ... %e A385577 1, 2, 6, 24, 120, 720, 5040, ... %e A385577 3, 8, 30, 144, 840, 5760, 45360, ... %e A385577 6, 20, 90, 504, 3360, 25920, 226800, ... %e A385577 10, 40, 210, 1344, 10080, 86400, 831600, ... %e A385577 ... %t A385577 A[n_,m_]:=n*Pochhammer[n+1,m+1]/(m+2); Table[A[n-m,m],{n,0,9},{m,0,n}]//Flatten %Y A385577 Cf. A000142, A001048, A002740, A006231, A007290, A068424, A238474. %Y A385577 Cf. A000217 (m=0), A033487 (m=2), A158874 (m=3). %Y A385577 Cf. A000004 (n=0). %K A385577 nonn,easy,tabl %O A385577 0,4 %A A385577 _Stefano Spezia_, Jul 03 2025