A112423 Number of 6-element subsets of {1,2,3,...,n} which have a sum-set with 14 elements.

6, 24, 42, 60, 78, 96, 114, 138, 162, 198, 234, 270, 306, 342, 384, 426, 468, 522, 576, 630, 684, 744, 804, 864, 924, 996, 1068, 1140, 1218, 1296, 1374, 1452, 1530, 1620, 1710, 1806, 1902, 1998, 2094, 2190, 2286, 2394

Offset

8,1

Links

Colin Barker, Table of n, a(n) for n = 8..1000

Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,0,0,1,0,-1,0,0,0,0,0,-1,1).

Formula

G.f.: 6*x^8/((1-x)^2*(1-x^7))+12*x^9/((1-x)^2*(1-x^8)).

Mathematica

DeleteCases[#, 0] &@ CoefficientList[Series[6 x^8/((1 - x)^2 (1 - x^7)) + 12 x^9/((1 - x)^2 (1 - x^8)), {x, 0, 49}], x] (* Michael De Vlieger, Jan 10 2017 *)

Prog

(PARI) Vec(6*x^8*(1 +3*x +3*x^2 +3*x^3 +3*x^4 +3*x^5 +3*x^6 +3*x^7) / ((1 -x)^3*(1 +x)*(1 +x^2)*(1 +x^4)*(1 +x +x^2 +x^3 +x^4 +x^5 +x^6)) + O(x^60)) \\ Colin Barker, Jan 10 2017

Crossrefs

Sequence in context: A061811 A252066 A031101 * A069541 A062768 A161333

Adjacent sequences: A112420 A112421 A112422 * A112424 A112425 A112426

Keyword

nonn,easy

Author

David S. Newman, Dec 10 2005

Extensions

Edited by Colin Barker, Jan 10 2017

a(11) corrected by Colin Barker, Jan 10 2017

Status

approved