cp's OEIS Frontend

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.

A163939 Triangle related to the o.g.f.s. of the right hand columns of A163934 (E(x,m=4,n)).

This page as a plain text file.
%I A163939 #10 Aug 13 2017 20:55:38
%S A163939 1,6,4,35,60,10,225,690,325,20,1624,7588,6762,1316,35,13132,85288,
%T A163939 120358,46928,4508,56,118124,1004736,2028660,1298860,265365,13896,84,
%U A163939 1172700,12529400,33896400,31862400,11077255,1313610,39915,120
%N A163939 Triangle related to the o.g.f.s. of the right hand columns of A163934 (E(x,m=4,n)).
%C A163939 The asymptotic expansions of the higher order exponential integral E(x,m=4,n) lead to triangle A163934, see A163931 for information on the E(x,m,n). The o.g.f.s. of the right hand columns of triangle A163934 have a nice structure Gf(p) = W4(z,p)/(1-z)^(2*p+2) with p = 1 for the first right hand column, p = 2 for the second right hand column, etc.. The coefficients of the W4(z,p) polynomials lead to the triangle given above, n >= 1 and 1 <= m <= n. The row sums of this triangle lead to A000457, see A163936 for more information.
%H A163939 G. C. Greubel, <a href="/A163939/b163939.txt">Table of n, a(n) for the first 50 rows, flattened</a>
%F A163939 a(n,m) = Sum_{k=0..(m-1)} (-1)^(n+k+1)*binomial(m-k+2,3)* binomial(2*n+2,k)*stirling1(m+n-k+1,m-k+2), for 1<= m <=n.
%e A163939 The first few W4(z,p) polynomials are:
%e A163939 W4(z,p=1) = 1/(1-z)^4
%e A163939 W4(z,p=2) = (6+4*z)/(1-z)^6
%e A163939 W4(z,p=3) = (35+60*z+10*z^2)/(1-z)^8
%e A163939 W4(z,p=4) = (225+690*z+325*z^2+20*z^3)/(1-z)^10
%p A163939 with(combinat): a := proc(n, m): add((-1)^(n+k+1)*((m-k+2)*(m-k+1)*(m-k)/3!)*binomial(2*n+2, k)*stirling1(m+n-k+1, m-k+2), k=0..m-1) end: seq(seq(a(n, m), m=1..n), n=1..8); # _Johannes W. Meijer_, revised Nov 27 2012
%t A163939 Table[Sum[(-1)^(n + k + 1)*Binomial[m - k + 2, 3]*Binomial[2*n + 2, k]*StirlingS1[m + n - k + 1, m - k + 2], {k, 0, m - 1}], {n, 1, 50}, {m, 1, n}] // Flatten (* _G. C. Greubel_, Aug 13 2017 *)
%o A163939 (PARI) for(n=1,10, for(m=1,n, print1(sum(k=0, m-1, (-1)^(n+k+1)* binomial(m-k+2,3)* binomial(2*n+2,k)*stirling(m+n-k+1,m-k+2,1)), ", "))) \\ _G. C. Greubel_, Aug 13 2017
%Y A163939 Row sums equal A000457.
%Y A163939 A000399 equals the first left hand column.
%Y A163939 A000292 equals the first right hand column.
%Y A163939 Cf. A163931 (E(x,m,n)) and A163934.
%Y A163939 Cf. A163936 (E(x,m=1,n)), A163937 (E(x,m=2,n)) and A163938 (E(x,m=3,n)).
%K A163939 easy,nonn,tabl
%O A163939 1,2
%A A163939 _Johannes W. Meijer_, Aug 13 2009