A109738 a(0)=1; for n>0, a(n) = a(n-1) S prime(n), where S is + if n is odd and a(n-1) is even, x if n is odd and a(n-1) is odd, - if n is even and a(n-1) is even, + if n is even and a(n-1) is odd.

1, 2, -1, -5, 2, 13, 26, 43, 62, 85, 114, 145, 182, 223, 266, 313, 366, 425, 486, 553, 624, 697, 776, 859, 948, 1045, 1146, 1249, 1356, 1465, 1578, 1705, 1836, 1973, 2112, 2261, 2412, 2569, 2732, 2899, 3072, 3251, 3432, 3623, 3816, 4013, 4212, 4423, 4646, 4873

Offset

0,2

Links

Table of n, a(n) for n=0..49.

Mathematica

f[l_] := Append[l, Apply[{Subtract, Plus, Plus, Times}[[2*Mod[Length[l], 2] + Mod[Last[l], 2] + 1]], {Last[l], Prime[Length[l]]}]]; Nest[f, {1}, 50] (* Ray Chandler *)

Crossrefs

A corrected version of A109623.

Sequence in context: A097131 A364487 A192263 * A258307 A343254 A143891

Adjacent sequences: A109735 A109736 A109737 * A109739 A109740 A109741

Keyword

sign

Author

N. J. A. Sloane, following a communication from Harry Yang (yexing_yang(AT)msn.com), Aug 11 2005

Extensions

Extended by Ray Chandler and Robert G. Wilson v, Aug 12 2005

Status

approved