A103731 Column k=4 sequence of array A103728.

1, 13, 191, 457, 1713, 2899, 6997, 19769, 26521, 57313, 89161, 109327, 159713, 265617, 417079, 479641, 709963, 903981, 1014697, 1408369, 1727987, 2305689, 3287713, 3882401, 4208317, 4921263, 5309929, 6155857, 9930313, 11272171

Offset

0,2

Comments

The two a(n) formulas, given below, produce natural numbers for all n>=0.

Links

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

Formula

a(n)=A103728(n+3, 4)=(1 +(p(n+3)-1)*binomial(p(n+3)-1, 4))/p(n+3), with p(n):=A000040(n) (n-th prime).

a(n)= (74 - 85*p(n+3) + 45*p(n+3)^2 - 11*p(n+3)^3 + p(n+3)^4)/4! = sum(A103718(k, m)*p(n+3)^m, m=0..4)/4!.

Crossrefs

Sequence in context: A318595 A055613 A123808 * A331495 A000563 A213698

Adjacent sequences: A103728 A103729 A103730 * A103732 A103733 A103734

Keyword

nonn,easy

Author

Wolfdieter Lang, Feb 24 2005

Status

approved