A397931 Number of n X n symmetric nonnegative integer matrices with each row sum nonzero and at most n.

1, 1, 9, 257, 24965, 8345689, 9935994469, 43261888985391, 701406030410472869, 42845177964745860920417, 9938256402369122699965809521, 8802585608898158202243879762364131, 29897291984353719865179845912465281152501, 390696408699742023679820463405166732774299014481

Offset

0,3

Links

Table of n, a(n) for n=0..13.

Crossrefs

Main diagonal of A397930.

Cf. A398070.

Sequence in context: A183493 A183424 A160073 * A157575 A072158 A001823

Adjacent sequences: A397927 A397929 A397930 * A397932 A397933 A397934

Keyword

nonn,new

Author

Andrew Howroyd, Jul 17 2026

Status

approved