A282083 Number of n-element subsets of [n+7] having an even sum.

1, 4, 16, 60, 170, 396, 848, 1716, 3235, 5720, 9696, 15912, 25236, 38760, 58080, 85272, 122661, 173052, 240240, 328900, 444158, 592020, 780208, 1017900, 1315015, 1682928, 2135744, 2689808, 3362600, 4173840, 5147328, 6310128, 7690953, 9321780, 11240400

Offset

0,2

Links

Alois P. Heinz, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (8, -32, 88, -188, 328, -480, 600, -646, 600, -480, 328, -188, 88, -32, 8, -1).

Formula

G.f.: (x^8-4*x^7+16*x^6-28*x^5+38*x^4-28*x^3+16*x^2-4*x+1) / ((x^2+1)^4*(x-1)^8).

a(n) = A282011(n+7,n).

Example

a(0) = 1: {}.
a(1) = 4: {2}, {4}, {6}, {8}.
a(2) = 16: {1,3}, {1,5}, {1,7}, {1,9}, {2,4}, {2,6}, {2,8}, {3,5}, {3,7}, {3,9}, {4,6}, {4,8}, {5,7}, {5,9}, {6,8}, {7,9}.

Crossrefs

Cf. A282011.

Sequence in context: A330791 A374096 A032094 * A261563 A265955 A217374

Adjacent sequences: A282080 A282081 A282082 * A282084 A282085 A282086

Keyword

nonn,easy,changed

Author

Alois P. Heinz, Feb 05 2017

Status

approved