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A125724 If "sumdigit" denotes the sum of the digits of a number then these are the numbers n such that n=sumdigit(sumdigit(n)^sumdigit(n)). 3
1, 13, 25, 45, 58, 88, 98 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Sequence is complete. - Giovanni Resta, Mar 21 2013

LINKS

Table of n, a(n) for n=1..7.

EXAMPLE

sumdigit(13)=4; 4^4 = 256; sumdigit(256)=13

MAPLE

P:=proc(n) local i, j, k, w; for i from 1 by 1 to n do w:=0; k:=i; while k>0 do w:=w+k-trunc(k/10)*10; k:=trunc(k/10); od; k:=w^w; w:=0; while k>0 do w:=w+k-trunc(k/10)*10; k:=trunc(k/10); od; if (i=w) then print(i, w); fi; od; end: P(100);

MATHEMATICA

sdQ[n_]:=Module[{sd=Total[IntegerDigits[n]]}, n==Total[ IntegerDigits[ sd^sd]]]; Select[Range[100], sdQ] (* Harvey P. Dale, Oct 22 2013 *)

CROSSREFS

Cf. A125526.

Sequence in context: A195558 A026058 A032697 * A277714 A163551 A005696

Adjacent sequences:  A125721 A125722 A125723 * A125725 A125726 A125727

KEYWORD

easy,fini,full,nonn,base

AUTHOR

Paolo P. Lava and Giorgio Balzarotti, Feb 02 2007

STATUS

approved

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Last modified September 23 15:06 EDT 2020. Contains 337310 sequences. (Running on oeis4.)