A095134 Sum of the product of the first floor(n/2) even-indexed primes and the product of the first floor(n/2) odd-indexed primes.

2, 5, 13, 31, 131, 383, 2143, 7057, 48197, 193433, 1483733, 6898961, 60231361, 293988703, 2808611363, 15253406999, 164272132459, 925319250199, 10930128162979, 65091314708809, 796351893424729, 5081275480436251

Offset

1,1

Links

Table of n, a(n) for n=1..22.

Formula

Sum_{i=1..n} of the product_{j=2..n, 2} p_j (A066206) and the product_{k=1..n, 2} p_j (A066205).

Example

a(5) = 2*5*11 + 3*7 = 131, a(6) = 2*5*11 + 3*7*13 = 383, a(7) =
2*5*11*17 + 3*7*13 = 2143, a(8) = 2*5*11*17 + 3*7*13*19 = 7057.

Mathematica

f[n_] := Product[Prime[i], {i, 2, n, 2}] + Product[Prime[i], {i, 1, n, 2}]; f[1] = 2; Table[ f[n], {n, 22}]

Crossrefs

Cf. A095137, A000040, A066206, A066205.

Sequence in context: A099515 A056367 A082733 * A086758 A179257 A116702

Adjacent sequences: A095131 A095132 A095133 * A095135 A095136 A095137

Keyword

nonn

Author

Robert G. Wilson v, May 27 2004

Status

approved