A281965 Number of sets of exactly n positive integers <= n+2 having a square element sum.

1, 1, 1, 2, 2, 2, 3, 4, 3, 3, 5, 4, 4, 5, 7, 5, 5, 9, 6, 6, 8, 9, 7, 7, 13, 8, 8, 12, 11, 9, 10, 15, 10, 10, 16, 13, 11, 14, 17, 12, 12, 20, 14, 13, 18, 19, 14, 15, 24, 15, 15, 22, 20, 16, 19, 26, 17, 17, 27, 20, 18, 23, 27, 19, 19, 33, 20, 20, 28, 27, 21, 23

Offset

0,4

Links

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

Formula

a(n) = A281871(n+2,n).

Example

a(7) = 4: {1,2,3,6,7,8,9}, {1,2,4,5,7,8,9}, {1,3,4,5,6,8,9}, {2,3,4,5,6,7,9}.
a(8) = 3: {1,2,3,4,5,6,7,8}, {1,3,5,6,7,8,9,10}, {2,3,4,6,7,8,9,10}.
a(9) = 3: {1,2,3,4,5,6,7,10,11}, {1,2,3,4,5,6,8,9,11}, {1,2,3,4,5,7,8,9,10}.

Crossrefs

A diagonal of A281871.

Sequence in context: A366655 A057748 A057747 * A228074 A152803 A347102

Adjacent sequences: A281962 A281963 A281964 * A281966 A281967 A281968

Keyword

nonn,look

Author

Alois P. Heinz, Feb 03 2017

Status

approved