A258385 a(n) = n^(n+1) * (n-1)^n.

0, 8, 648, 82944, 16000000, 4374000000, 1613775332736, 773738492592128, 467988280328060928, 348678440100000000000, 313842837672100000000000, 335790511878017502425382912, 421272520289832237611045879808, 612530145817540311016457192308736

Offset

1,2

Links

Daniel Suteu, Table of n, a(n) for n = 1..20

Formula

a(n) ~ 1/e * n^(2n+1). - Charles R Greathouse IV, May 28 2015

a(n) = A007778(n)*A007778(n-1). - Michel Marcus, Jul 07 2015

Example

For n=3, a(3) = 3^(3+1) * (3-1)^3 = 3^4 * 2^3 = 81 * 8 = 648.

Mathematica

Array[#^(# + 1) (# - 1)^# &, 20] (* Vincenzo Librandi, May 29 2015 *)

Prog

(Sidef)
func a(n) {
    (n-1)**n * n**(n+1);
};
1.to(Math.inf).each { |n|
    say a(n);
};
(PARI) a(n)=n^(n+1)*(n-1)^n \\ Charles R Greathouse IV, May 28 2015
(Magma) [n^(n+1) * (n-1)^n: n in [1..20]]; // Vincenzo Librandi, May 29 2015

Crossrefs

Cf. A007778 (n^(n+1)).

Sequence in context: A196800 A196588 A197045 * A352593 A267968 A253268

Adjacent sequences: A258382 A258383 A258384 * A258386 A258387 A258388

Keyword

nonn,easy

Author

Daniel Suteu, May 28 2015

Extensions

More terms from Vincenzo Librandi, May 29 2015

Status

approved