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A080692 a(n)=(-1)^(n+1)*det(M(n)) where M(n) is the n X n matrix M(i,j)=min(abs(i-j),i). 0
0, 1, 3, 8, 18, 40, 88, 192, 400, 832, 1728, 3584, 7424, 15360, 31744, 65536, 133120, 270336, 548864, 1114112, 2260992, 4587520, 9306112, 18874368, 38273024, 77594624, 157286400, 318767104, 645922816, 1308622848, 2650800128 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

A001787(n-1) is the determinant of the n X n matrix M(i,j)=min(abs(i-j),i+j)

LINKS

Table of n, a(n) for n=1..31.

FORMULA

a(n)=2*a(n-1)-2^floor(n-log(n)/log(2)-1)=2*a(n-1)-A054243(n)

EXAMPLE

M(5) is [0 1 1 1 1] [1 0 1 2 2] [2 1 0 1 2] [3 2 1 0 1] [4 3 2 1 0].

PROG

(PARI) a(n)=(-1)^(n+1)*matdet(matrix(n, n, i, j, min(abs(i-j), i))

CROSSREFS

Cf. A054243, A001787.

Sequence in context: A026657 A036384 A294591 * A117080 A240135 A066425

Adjacent sequences:  A080689 A080690 A080691 * A080693 A080694 A080695

KEYWORD

nonn

AUTHOR

Benoit Cloitre, Mar 03 2003

STATUS

approved

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Last modified May 14 09:31 EDT 2021. Contains 343879 sequences. (Running on oeis4.)