A309884 - OEIS

%I #27 Sep 08 2022 08:46:22

%S 0,1,10,74,100,740,1000,3488,7400,10000,23658,30868,34880,47508,48517,

%T 52187,58947,59468,67685,68058,74000,76814,78368,78845,84878,100000,

%U 108478,145877,149217,163871,179685,186884,188647,218977,219878,236580,238758,248967,278638,292597,308680

%N Numbers k such that A003132(k^3) = A003132(k), where A003132(n) is the sum of the squares of the digits of n.

%C If k is in the sequence, then so are k*10^r, with r >= 1.

%e 74^3 = 405224, A003132(74) = 7^2 + 4^2 = 65, A003132(405224) = 4^2 + 0^2 + 5^2 + 2^2 + 2^2 + 4^2 = 65.

%t digSum[n_] := Total[IntegerDigits[n]^2]; Select[Range[0, 310000], digSum[#] == digSum[#^3] &] (* _Amiram Eldar_, Aug 22 2019 *)

%o (PARI) for(i = 0, 400000, if(norml2(digits(i^3)) == norml2(digits(i)), print1(i, ", ")))

%o (Magma) [0] cat [k:k in [1..310000]| &+[c^2: c in Intseq(k)] eq &+[c^2: c in Intseq(k^3)]]; // _Marius A. Burtea_, Aug 26 2019

%Y Cf. A003132, A058369, A070276, A174460, A176670, A178213, A307735, A309883.

%K nonn,base

%O 1,3

%A _Antonio Roldán_, Aug 21 2019