A268228 - OEIS

%I #22 Sep 08 2022 08:46:15

%S 1,9,7,13,9,4,16,9,19,10,9,16,13,18,13,16,18,10,19,9,16,22,9,13,7,9,

%T 19,10,18,16,13,27,13,25,18,10,19,18,25,13,18,31,16,27,19,19,27,16,22,

%U 18,4,16,9,19,19,9,25,13,27,13,16,18,19,19,18,16,31,18,31,16,27,19,10,18,7,13,18

%N a(n) = sum of digits of (2n + 1)^2.

%H Robert Israel, <a href="/A268228/b268228.txt">Table of n, a(n) for n = 0..10000</a>

%H H. I. Okagbue, M. O. Adamu, S. A. Iyase, A. A. Opanuga, <a href="http://dx.doi.org/10.17485/ijst/2015/v8i15/69912">Sequence of Integers Generated by Summing the Digits of their Squares</a>, Indian Journal of Science and Technology, Vol 8(15), DOI: 10.17485/ijst/2015/v8i15/69912, July 2015.

%F a(n) = A007953(A016754(n)). - _Michel Marcus_, Oct 13 2017

%p f:= n -> convert(convert((2*n+1)^2,base,10),`+`):

%p map(f, [$0..100]); # _Robert Israel_, Apr 26 2020

%t Table[Sum[DigitCount[(2 n + 1)^2] [[i]] i, {i, 9}], {n, 0, 70}] (* _Vincenzo Librandi_, Jul 23 2016, after _G. C. Greubel_ *)

%o (PARI) a(n) = sumdigits((2*n+1)^2); \\ _Michel Marcus_, Jul 23 2016

%o (Magma) [&+Intseq((2*n+1)^2): n in [0..87] ]; // _Vincenzo Librandi_, Jul 23 2016

%Y Bisection of A004159. Cf. A007953, A016754, A268227.

%K nonn,base

%O 0,2

%A _N. J. A. Sloane_, Jan 31 2016