cp's OEIS Frontend

A262711 Numbers k such that sum of digits of k^2 is 7.

%I A262711 #24 Jun 18 2025 13:14:05
%S A262711 4,5,32,40,49,50,149,320,400,490,500,1049,1490,3200,4000,4900,5000,
%T A262711 10490,14900,32000,40000,49000,50000,104900,149000,320000,400000,
%U A262711 490000,500000,1049000,1490000,3200000,4000000,4900000,5000000,10490000,14900000
%N A262711 Numbers k such that sum of digits of k^2 is 7.
%C A262711 Subsequence of A156638. [_Bruno Berselli_, Sep 28 2015]
%e A262711 4 is in sequence because 4^2 = 16 and 1+6 = 7.
%t A262711 Select[Range[10^7], Total[IntegerDigits[#^2]] == 7 &]
%o A262711 (Magma) [n: n in [1..2*10^7] | &+Intseq(n^2) eq 7];
%o A262711 (PARI) for(n=1, 1e8, if (sumdigits(n^2) == 7, print1(n", "))) \\ _Altug Alkan_, Sep 28 2015
%Y A262711 Cf. sum of digits of n^2 is k: A052216 (k=4), this sequence (k=7), A262712 (k=9), A262713 (k=10).
%Y A262711 Cf. A004159, A061910, A156638.
%Y A262711 Cf. A215614.
%K A262711 nonn,base
%O A262711 1,1
%A A262711 _Vincenzo Librandi_, Sep 28 2015