A080291 a(n)=(-1)^(n+1)n^n(n+(1/12)(n^2-1)).

1, -9, 99, -1344, 21875, -416016, 9058973, -222298112, 6069587661, -182500000000, 5991545082831, -213243402387456, 8177627877990831, -336138206473129984, 14742427642822265625, -687141216745680797696, 33916850737339807331257

Offset

1,2

Comments

a(n) is the determinant of the n X n matrix M with M(i,i)=2i-n, M(i.j)=i+j.

Links

Table of n, a(n) for n=1..17.

Formula

a(n)=(-1)^(n+1)n^n(n+(1/12)(n^2-1)). a(n)=(-1)^n(n^n-n^(n-1)A002378(n)-n^(n-2)A002415(n)).

Mathematica

Table[(-1)^(n + 1)n^n(n + (n^2 - 1)/12), {n, 1, 17}]

Crossrefs

Sequence in context: A015685 A051581 A356100 * A215243 A113395 A070068

Adjacent sequences: A080288 A080289 A080290 * A080292 A080293 A080294

Keyword

easy,sign

Author

Mario Catalani (mario.catalani(AT)unito.it), Feb 13 2003

Status

approved