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A138908 a(n) = d^d, where d is the number of digits in n. 3
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27, 27 (list; graph; refs; listen; history; text; internal format)
OFFSET
0,11
LINKS
FORMULA
From Amiram Eldar, Nov 18 2020: (Start)
a(n) = A055642(n)^A055642(n).
Sum_{n>=1} 1/a(n) = A308314. (End)
MATHEMATICA
dd[n_]:=Module[{d=IntegerLength[n]}, d^d]; Join[{1}, Array[dd, 150]] (* Harvey P. Dale, Mar 16 2013 *)
PROG
(PARI) a(n) = my(d=#Str(n)); d^d; \\ Michel Marcus, Nov 18 2020
CROSSREFS
Sequence in context: A251539 A123932 A010709 * A032564 A141248 A273339
KEYWORD
easy,nonn,base
AUTHOR
Odimar Fabeny, May 16 2008
EXTENSIONS
Edited by N. J. A. Sloane, Sep 29 2011, at the suggestion of Franklin T. Adams-Watters
STATUS
approved

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Last modified April 17 02:36 EDT 2024. Contains 371756 sequences. (Running on oeis4.)