OFFSET
1,3
COMMENTS
Perfect powers m > 1 such that the sum of the digits of m equals one of its nontrivial roots.
Essentially a duplicate of A023106, where numbers 2 through 9 are allowed as solutions for k=1.
EXAMPLE
234256 = 22^4 and 2+3+4+2+5+6 = 22, hence 234256 is a term.
390625 = 25^4 and 3+9+0+6+2+5 = 25, hence 390625 is a term.
PROG
(PARI) {m=10^5; z=10^11; v=[]; for(n=0, m, k=2; while((p=n^k)<=z, s=sumdigits(p); if(n==s, v=concat(v, p)); k++)); v=vecsort(v); print(v)} \\ Klaus Brockhaus, Apr 24 2007, edited by M. F. Hasler, Apr 14 2015
(PARI) is(n)=ispower(n)&&(1<s=sumdigits(n))&&n==s^round(log(n)/log(s))||n<2 \\ M. F. Hasler, Apr 14 2015
CROSSREFS
KEYWORD
nonn,base
AUTHOR
J. M. Bergot, Apr 23 2007
EXTENSIONS
Edited, corrected and extended by Klaus Brockhaus, Apr 24 2007
Definition simplified and initial terms 0, 1 added by M. F. Hasler, Apr 14 2015
STATUS
approved