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A268228 a(n) = sum of digits of (2n + 1)^2. 2
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, 19, 10, 18, 16, 13, 27, 13, 25, 18, 10, 19, 18, 25, 13, 18, 31, 16, 27, 19, 19, 27, 16, 22, 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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Robert Israel, Table of n, a(n) for n = 0..10000

H. I. Okagbue, M. O. Adamu, S. A. Iyase, A. A. Opanuga, Sequence of Integers Generated by Summing the Digits of their Squares, Indian Journal of Science and Technology, Vol 8(15), DOI: 10.17485/ijst/2015/v8i15/69912, July 2015.

FORMULA

a(n) = A007953(A016754(n)). - Michel Marcus, Oct 13 2017

MAPLE

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

map(f, [$0..100]); # Robert Israel, Apr 26 2020

MATHEMATICA

Table[Sum[DigitCount[(2 n + 1)^2] [[i]] i, {i, 9}], {n, 0, 70}] (* Vincenzo Librandi, Jul 23 2016, after G. C. Greubel *)

PROG

(PARI) a(n) = sumdigits((2*n+1)^2); \\ Michel Marcus, Jul 23 2016

(MAGMA) [&+Intseq((2*n+1)^2): n in [0..87] ]; // Vincenzo Librandi, Jul 23 2016

CROSSREFS

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

Sequence in context: A121911 A010547 A011405 * A131724 A190995 A186830

Adjacent sequences:  A268225 A268226 A268227 * A268229 A268230 A268231

KEYWORD

nonn,base

AUTHOR

N. J. A. Sloane, Jan 31 2016

STATUS

approved

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Last modified October 21 17:37 EDT 2021. Contains 348155 sequences. (Running on oeis4.)