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

Author

Wolfdieter Lang, Feb 24 2005

Keywords

• nonn
• easy

Comments

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

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!.