A282517 Number of n-element subsets of [2n] having a prime element sum.

0, 1, 4, 6, 21, 59, 239, 760, 2970, 10060, 38930, 124735, 503767, 1986024, 7059818, 27806989, 107739266, 376458328, 1421570461, 5750402871, 23095812036, 89360066340, 315720338715, 1202284699132, 5133364318360, 20343420316531, 74430884941912, 279471388089807

Offset

0,3

Links

Alois P. Heinz, Table of n, a(n) for n = 0..130

Formula

a(n) = A282516(2n,n).

Example

a(1) = 1: {2}.
a(2) = 4: {1,2}, {1,4}, {2,3}, {3,4}.
a(3) = 6: {1,2,4}, {1,4,6}, {2,3,6}, {2,4,5}, {2,5,6}, {3,4,6}.
a(4) = 21: {1,2,3,5}, {1,2,3,7}, {1,2,4,6}, {1,2,6,8}, {1,3,4,5}, {1,3,5,8}, {1,3,6,7}, {1,3,7,8}, {1,4,5,7}, {1,4,6,8}, {1,5,6,7}, {2,3,4,8}, {2,3,5,7}, {2,3,6,8}, {2,4,5,6}, {2,4,5,8}, {2,4,6,7}, {2,6,7,8}, {3,4,5,7}, {3,5,7,8}, {4,5,6,8}.

Crossrefs

Cf. A282516.

Sequence in context: A323845 A229743 A151520 * A227249 A002270 A286358

Adjacent sequences: A282514 A282515 A282516 * A282518 A282519 A282520

Keyword

nonn

Author

Alois P. Heinz, Feb 17 2017

Status

approved