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A162110 Number of n X n symmetric binary arrays with rows, considered as graycode numbers, in strictly increasing order, and no more than 2 ones in any row or column 0
2, 4, 8, 21, 53, 145, 405, 1180, 3562, 11030, 35306, 115338, 387443, 1326992, 4650201, 16604351, 60443887, 223971602, 844095896, 3234044019, 12582749734, 49703821584, 199149007691, 809153896365, 3331563584486 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..25.

CROSSREFS

Sequence in context: A001315 A216643 A002040 * A108071 A055876 A065847

Adjacent sequences:  A162107 A162108 A162109 * A162111 A162112 A162113

KEYWORD

nonn

AUTHOR

R. H. Hardin Jun 25 2009

STATUS

approved

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Last modified December 13 03:41 EST 2019. Contains 329968 sequences. (Running on oeis4.)