

A022899


Number of solutions to c(1)*prime(2) + ... + c(n)*prime(n+1) = 2, where c(i) = +1 for i>1, c(1) = 1.


1



0, 0, 0, 1, 0, 0, 0, 4, 0, 9, 0, 14, 0, 75, 0, 155, 0, 724, 0, 2376, 0, 6900
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OFFSET

1,8


LINKS

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


EXAMPLE

a(8) counts these 4 solutions: {3, 5, 7, 11, 13, 17, 19, 23}, {3, 5, 7, 11, 13, 17, 19, 23}, {3, 5, 7, 11, 13, 17, 19, 23}, {3, 5, 7, 11, 13, 17, 19, 23}.


MATHEMATICA

{f, s} = {2, 2}; Table[t = Map[Prime[# + f  1] &, Range[2, z]]; Count[Map[Apply[Plus, #] &, Map[t # &, Tuples[{1, 1}, Length[t]]]], s  Prime[f]], {z, 22}]
(* A022899, a(n) = number of solutions of "sum = s" using Prime(f) to Prime(f+n1) *)
n = 8; t = Map[Prime[# + f  1] &, Range[n]]; Map[#[[2]] &, Select[Map[{Apply[Plus, #], #} &, Map[t # &, Map[Prepend[#, 1] &, Tuples[{1, 1}, Length[t]  1]]]], #[[1]] == s &]] (* the 4 solutions of using n=8 primes; Peter Moses, Oct 01 2013 *)


CROSSREFS

Sequence in context: A013496 A187172 A241667 * A081148 A187606 A138478
Adjacent sequences: A022896 A022897 A022898 * A022900 A022901 A022902


KEYWORD

nonn


AUTHOR

Clark Kimberling


EXTENSIONS

Corrected and extended by Clark Kimberling, Oct 01 2013


STATUS

approved



