A281969 Number of sets of exactly n positive integers <= n+6 having a square element sum.

1, 2, 5, 11, 23, 43, 74, 124, 197, 296, 434, 627, 875, 1188, 1600, 2128, 2755, 3522, 4511, 5661, 6983, 8637, 10610, 12781, 15343, 18497, 21937, 25751, 30416, 35702, 41266, 47772, 55531, 63578, 72405, 83101, 94662, 106544, 120507, 136663, 152742, 170490, 191873

Offset: 0

Author

Alois P. Heinz, Feb 03 2017

Keywords

• nonn

Examples

			a(4) = 23: {1,2,3,10}, {1,2,4,9}, {1,2,5,8}, {1,2,6,7}, {1,3,4,8}, {1,3,5,7}, {1,4,5,6}, {1,5,9,10}, {1,6,8,10}, {1,7,8,9}, {2,3,4,7}, {2,3,5,6}, {2,4,9,10}, {2,5,8,10}, {2,6,7,10}, {2,6,8,9}, {3,4,8,10}, {3,5,7,10}, {3,5,8,9}, {3,6,7,9}, {4,5,6,10}, {4,5,7,9}, {4,6,7,8}.
		

Links

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

Crossrefs

A diagonal of A281871.

Programs

Mathematica

Table[Count[Subsets[Range[n+6],{n}],?(IntegerQ[Sqrt[Total[#]]]&)],{n,0,50}] (* _Harvey P. Dale, Aug 21 2017 *)

Formula

a(n) = A281871(n+6,n).