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A282083
Number of n-element subsets of [n+7] having an even sum.
2
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
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
KEYWORD
nonn,easy
AUTHOR
Alois P. Heinz, Feb 05 2017
STATUS
approved