OFFSET
1,1
COMMENTS
The sequence is finite because the restricted sum of divisors of n, for n composite, is at least sqrt(n), while the sum of the fourth powers of the digits of n is at most 9^4*log_10(n+1). Last term is a(101) = 163998389. - Giovanni Resta, Oct 05 2018
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..101 (full sequence)
EXAMPLE
1005 is in the sequence because 1^4 + 0^4 + 0^4 + 5^4 = 626, and the sum of the divisors 1< d<1005 is 3 + 5 +15 + 67 + 201+ 335 = 626.
MATHEMATICA
Q[n_]:=Module[{a=Total[Rest[Most[Divisors[n]]]]}, a == Total[IntegerDigits[n]^4]]; Select[Range[2, 10^7], Q]
CROSSREFS
KEYWORD
nonn,base,fini,full
AUTHOR
Michel Lagneau, Dec 15 2011
EXTENSIONS
Keywords fini and full added by Giovanni Resta, Oct 05 2018
STATUS
approved