cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-2 of 2 results.

A007778 a(n) = n^(n+1).

Original entry on oeis.org

0, 1, 8, 81, 1024, 15625, 279936, 5764801, 134217728, 3486784401, 100000000000, 3138428376721, 106993205379072, 3937376385699289, 155568095557812224, 6568408355712890625, 295147905179352825856, 14063084452067724991009, 708235345355337676357632
Offset: 0

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Author

Keywords

Comments

Number of edges of the complete bipartite graph of order n+n^n, K_n,n^n. - Roberto E. Martinez II, Jan 07 2002
All rational solutions to the equation x^y = y^x, with x < y, are given by x = A000169(n+1)/A000312(n), y = A000312(n+1)/A007778(n), where n >= 1. - Nick Hobson, Nov 30 2006
a(n) is also the number of ways of writing an n-cycle as the product of n+1 transpositions. - Nikos Apostolakis, Nov 22 2008
a(n) is the total number of elements whose preimage is the empty set summed over all partial functions from [n] into [n]. - Geoffrey Critzer, Jan 12 2022

References

  • Clifford A. Pickover, A Passion for Mathematics, Wiley, 2005; see p. 67.

Crossrefs

Essentially the same as A065440.
Cf. A061250, A143857. [From Reinhard Zumkeller, Jul 23 2010]

Programs

Formula

E.g.f.: -W(-x)/(1 + W(-x))^3, W(x) Lambert's function (principal branch).
a(n) = Sum_{k=0..n} binomial(n,k)*A000166(k+1)*(n+1)^(n-k). - Peter Luschny, Jul 09 2010
See A008517 and A134991 for similar e.g.f.s. and A048993. - Tom Copeland, Oct 03 2011
E.g.f.: d/dx {x/(T(x)*(1-T(x)))}, where T(x) = Sum_{n >= 1} n^(n-1)*x^n/n! is the tree function of A000169. - Peter Bala, Aug 05 2012
a(n) = n*A000312(n). - R. J. Mathar, Jan 12 2017
Sum_{n>=2} 1/a(n) = A135608. - Amiram Eldar, Nov 17 2020

A061250 a(n) = (n-2)*(n-1)^n.

Original entry on oeis.org

0, 0, 8, 162, 3072, 62500, 1399680, 34588806, 939524096, 27894275208, 900000000000, 31384283767210, 1176925259169792, 47248516628391468, 2022385242251558912, 91957716979980468750, 4427218577690292387840, 225009351233083599856144, 12040000871040740498079744
Offset: 1

Views

Author

Gero Burghardt (gerogoestohollywood(AT)yahoo.de), Jun 01 2001

Keywords

Crossrefs

Cf. A143857. [From Reinhard Zumkeller, Jul 23 2010]

Programs

Extensions

More terms from Klaus Brockhaus and Larry Reeves (larryr(AT)acm.org), Jun 03 2001
Showing 1-2 of 2 results.