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 A128912 Numbers m of the form (sum of digits of m)^k, k > 1. 1
 0, 1, 81, 512, 2401, 4913, 5832, 17576, 19683, 234256, 390625, 614656, 1679616, 17210368, 34012224, 52521875, 60466176, 205962976, 612220032, 8303765625, 10460353203, 24794911296, 27512614111, 52523350144, 68719476736 (list; graph; refs; listen; history; text; internal format)
 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. LINKS Table of n, a(n) for n=1..25. 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

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Last modified September 15 19:05 EDT 2024. Contains 375954 sequences. (Running on oeis4.)