A127768 - OEIS

A127768

Row sums of the inverse of number triangle A(n,k) = 1/C(n) if k <= n <= 2k, 0 otherwise, where C(n) = A000108(n).

1, 1, 1, 4, 9, 29, 90, 301, 1001, 3441, 11934, 42019, 149226, 534978, 1931540, 7020706, 25662825, 94288121, 347993910, 1289627931, 4796857230, 17902158534, 67016296620, 251577092029, 946844533674, 3572042403354, 13505406670700, 51166198378830, 194214400834356, 738494266832548

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OFFSET

0,4

LINKS

Table of n, a(n) for n=0..29.

FORMULA

a(2n) = A127769(n).

PROG

(PARI) a(n) = {n++; my(m = matrix(n+1, n+1, i, j, i--; j--; if ((i >= j) && (i <= 2*j), (i+1)/binomial(2*i, i), 0))); m = m^(-1); vecsum(m[n, ]); } \\ Michel Marcus, Sep 30 2018

CROSSREFS

Cf. A000108.

Row sums of A127767.

Bisections: A127769, A127770.

Sequence in context: A276984 A210969 A059345 * A231255 A241393 A186650

Adjacent sequences: A127765 A127766 A127767 * A127769 A127770 A127771

KEYWORD

nonn

AUTHOR

Paul Barry, Jan 28 2007

EXTENSIONS

More terms from Michel Marcus, Sep 30 2018

STATUS

approved