A338235 Numbers k such that k + the sum of the 4th powers of the decimal digits of k is a square.

20, 47, 104, 113, 228, 255, 333, 544, 632, 743, 1054, 1122, 1518, 1762, 1901, 2071, 3617, 4317, 4432, 4456, 4513, 4557, 4727, 4927, 5000, 5058, 5080, 5173, 5473, 5847, 6047, 6767, 6832, 7247, 7408, 7453, 7487, 7518, 7921, 7997, 8127, 8958, 9208, 9487, 10917

Offset: 1

Author

Will Gosnell, Jan 30 2021

Keywords

• base
• nonn

Examples

			20 is a member since 2^4 + 0^4 + 20 = 6^2,
47 is a member since 4^4 + 7^4 + 47 = 52^2,
104 is a member since 1^4 + 0^4 + 4^4 = 104 = 19^2,
113 is a member since 1^4 + 1^4 + 3^4 + 113 = 14^2.
		

Crossrefs

Cf. A055013, A329179, A329386.

Programs

Maple

filter:= proc(n) local L,k;
  issqr(n + add(t^4, t=convert(n,base,10)))
end proc:
select(filter, [$1..20000]); # Robert Israel, Jan 30 2021