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

0,2

Links

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

Formula

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

Example

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}.

Mathematica

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

Crossrefs

A diagonal of A281871.

Sequence in context: A186265 A225947 A330909 * A124920 A064934 A227637

Adjacent sequences: A281966 A281967 A281968 * A281970 A281971 A281972

Keyword

nonn

Author

Alois P. Heinz, Feb 03 2017

Status

approved