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A259489
Numbers n such that n plus the cube of sum of digits of n is a perfect square.
1
17, 38, 131, 171, 360, 392, 500, 512, 605, 729, 863, 1031, 1035, 1481, 1737, 1994, 2156, 2268, 2483, 2513, 2520, 2732, 2817, 3011, 3240, 3384, 3449, 3710, 3881, 3923, 4032, 4100, 4112, 4145, 4572, 5193, 5456, 5598, 5720, 5832, 5903, 5924, 7164, 7388, 7625, 7631
OFFSET
1,1
COMMENTS
All the terms are congruent to 2 or 0 (mod 3).
LINKS
EXAMPLE
a(3) = 131: 131 + (1 + 3 + 1)^3 = 256 = 16^2.
a(4) = 171: 171 + (1 + 7 + 1)^3 = 900 = 30^2.
MATHEMATICA
Select[Range[50000], IntegerQ[Sqrt[# +Plus@@(IntegerDigits[#])^3]]&]
PROG
(PARI) for(n = 1, 10^5, if(issquare(sumdigits(n)^3 + n), print1(n, ", ")))
(Magma) [ n: n in [1..10^4] | IsSquare(&+Intseq(n)^3 + n) ] ;
CROSSREFS
KEYWORD
nonn,base
AUTHOR
K. D. Bajpai, Jun 28 2015
STATUS
approved