A071548 - OEIS

A071548

Determinant of the n X n matrix whose element (i,j) equals f(|i-j|) where f(n) is 1 if the sum of middle divisors (A071090) > 0, else 0.

0, -1, 2, 0, 0, 0, 2, 1, -4, 12, 0, -12, -4, 7, 44, 48, 0, -48, 44, 345, 334, -1196, 2328, 4796, 8022, -35417, 123840, -118503, 89082, 48160, -414248, 2107104, -2358342, -27802725, -168156872, 415198413, 804518348, -2450715149, -711441100, 3648319725, -2721771200, -17289389524, 205130688

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OFFSET

1,3

LINKS

Table of n, a(n) for n=1..43.

MATHEMATICA

f[n_] := If[n > 0, If[Plus @@ Select[ Divisors[n], Sqrt[n/2] <= # < Sqrt[n*2] &] == 0, 0, 1], 0]; Table[ Det[ Table[ f[ Abs[i - j]], {i, 1, n}, {j, 1, n}]], {n, 1, 50}]

CROSSREFS

Cf. A071090.

Sequence in context: A374207 A100699 A108921 * A369309 A216228 A372602

Adjacent sequences: A071545 A071546 A071547 * A071549 A071550 A071551

KEYWORD

sign

AUTHOR

Robert G. Wilson v, May 30 2002

STATUS

approved