

A163937


Triangle related to the o.g.f.s. of the right hand columns of A028421 (E(x,m=2,n))


4



1, 1, 2, 2, 10, 3, 6, 52, 43, 4, 24, 308, 472, 136, 5, 120, 2088, 4980, 2832, 369, 6, 720, 16056, 53988, 49808, 13638, 918, 7, 5040, 138528, 616212, 826160, 381370, 57540, 2167, 8, 40320, 1327392, 7472952, 13570336, 9351260, 2469300, 222908, 4948, 9
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OFFSET

1,3


COMMENTS

The asymptotic expansions of the higher order exponential integral E(x,m=2,n) lead to triangle A028421, see A163931 for information on the E(x,m,n). The o.g.f.s. of the right hand columns of triangle A028421 have a nice structure Gf(p) = W2(z,p)/(1z)^(2*p) with p = 1 for the first right hand column, p = 2 for the second right hand column, etc.. The coefficients of the W2(z,p) polynomials lead to the triangle given above, n >= 1 and 1 <= m <= n. The row sums of this triangle lead to A001147 (minus a(0)), see A163936 for more information.


LINKS

Table of n, a(n) for n=1..45.


FORMULA

a(n,m) = sum((1)^(n+k+1)*((mk)/1!)*binomial(2*n,k)*stirling1(m+nk1,mk),k=0..m1)


EXAMPLE

The first few W2(z,p) polynomials are:
W2(z,p=1) = 1/(1z)^2
W2(z,p=2) = (1+2*z)/(1z)^4
W2(z,p=3) = (2+10*z+3*z^2)/(1z)^6
W2(z,p=4) = (6+52*z+43*z^2+4*z^3)/(1z)^8


MAPLE

with(combinat): a := proc(n, m): add((1)^(n+k+1)*((mk)/1!)*binomial(2*n, k)*stirling1(m+nk1, mk), k=0..m1) end: seq(seq(a(n, m), m=1..n), n=1..9); # [Johannes W. Meijer, revised Nov 27 2012]


CROSSREFS

Row sums equal A001147 (n>=1).
A000142, 2*A001705, are the first two left hand columns.
A000027 is the first right hand column.
Cf. A163931 (E(x,m,n)) and A028421.
Cf. A163936 (E(x,m=1,n)), A163938 (E(x,m=3,n)) and A163939 (E(x,m=4,n)).
Sequence in context: A038036 A133631 A137450 * A083457 A163808 A223126
Adjacent sequences: A163934 A163935 A163936 * A163938 A163939 A163940


KEYWORD

easy,nonn,tabl


AUTHOR

Johannes W. Meijer, Aug 13 2009


STATUS

approved



