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A226238
a(n) = (n^n - n)/(n - 1).
5
2, 12, 84, 780, 9330, 137256, 2396744, 48427560, 1111111110, 28531167060, 810554586204, 25239592216020, 854769755812154, 31278135027204240, 1229782938247303440, 51702516367896047760, 2314494592664502210318, 109912203092239643840220
OFFSET
2,1
COMMENTS
a(n) expressed in base n is written with (n-1) ones followed by a zero. - Michel Marcus, Aug 25 2013
LINKS
Tanya Khovanova and Gregory Marton, Archive Labeling Sequences, arXiv:2305.10357 [math.HO], 2023. See p. 9.
FORMULA
a(n) = Sum_{k=1..n-1} n^k.
a(n) = A023037(n) - 1, for n>1. - Michel Marcus, Aug 25 2013
MATHEMATICA
Array[(#^# - #)/(# - 1) &, 18, 2] (* Michael De Vlieger, May 24 2023 *)
PROG
(PARI) a(n)=(n^n-n)/(n-1)
(Python)
def A226238(n): return (n**n-n)//(n-1) # Chai Wah Wu, Sep 28 2023
CROSSREFS
A diagonal of A228275.
Sequence in context: A362237 A052887 A052867 * A179495 A348765 A364279
KEYWORD
nonn,easy
AUTHOR
Ralf Stephan, Aug 25 2013
STATUS
approved