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
Vaclav Kotesovec, Table of n, a(n) for n = 1..1000
Vaclav Kotesovec, Graph - the asymptotic ratio (10000 terms)
FORMULA
a(n) = 2*a(n-1) + 2^floor(n-log(n)/log(2)-1) = 2*a(n-1) + A054243(n). [corrected by Vaclav Kotesovec, Aug 23 2024]
a(n) ~ 2^(n-1) * (c*(log(n) + gamma) - 1), where gamma is the Euler-Mascheroni constant A001620 and 1/2 < c < 1. Conjecture: c = 1/sqrt(2). - Vaclav Kotesovec, Aug 23 2024
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].
MATHEMATICA
Table[(-1)^(n+1) * Det[Table[Min[Abs[i-j], i], {i, 1, n}, {j, 1, n}]], {n, 1, 30}] (* Vaclav Kotesovec, Aug 23 2024 *)
PROG
(PARI) a(n)=(-1)^(n+1)*matdet(matrix(n, n, i, j, min(abs(i-j), i)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Benoit Cloitre, Mar 03 2003
STATUS
approved