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A109966 8^((n^2-n)/2). 3
1, 1, 8, 512, 262144, 1073741824, 35184372088832, 9223372036854775808, 19342813113834066795298816, 324518553658426726783156020576256, 43556142965880123323311959751266331066368 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

Sequence given by the Hankel transform (see A001906 for definition) of A082147 = {1, 1, 9, 89, 945, 10577, 123129, 1476841, ...}; example : det([1, 1, 9, 89; 1, 9, 89, 945; 9, 89, 945, 10577; 89, 945, 10577, 123129]) = 8^6 = 262144.

Hankel transform of A059435 = [1, 2, 12, 88, 720, 6304, ...] . - Philippe Deléham, Sep 03 2006

The number of labeled graphs (with no self loops) such that at most three edges connect any vertex pair. - Geoffrey Critzer, Nov 10 2011

LINKS

Table of n, a(n) for n=0..10.

FORMULA

a(n+1) is the determinant of n X n matrix M_(i, j) = binomial(8i, j).

Hankel transform of A059435 = [1, 2, 12, 88, 720, 6304, ...] . - Philippe Deléham, Sep 03 2006

MATHEMATICA

Table[2^(3*Binomial[n, 2]), {n, 0, 10}] (* Geoffrey Critzer, Nov 10 2011 *)

PROG

(PARI) a(n)=8^binomial(n, 2) \\ Charles R Greathouse IV, Jan 17 2012

CROSSREFS

Cf. A006125, A047656, A053763, A053764, A109345, A109354, A109493.

Sequence in context: A145259 A154025 A013713 * A139567 A035131 A067512

Adjacent sequences:  A109963 A109964 A109965 * A109967 A109968 A109969

KEYWORD

nonn,easy

AUTHOR

Philippe Deléham, Sep 01 2005

STATUS

approved

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Last modified December 18 15:56 EST 2014. Contains 252163 sequences.