A159879 Numbers n such that digit sum of n^2 is 2*(digit sum of n).

0, 2, 11, 20, 27, 36, 54, 72, 74, 81, 92, 101, 108, 110, 128, 135, 144, 153, 162, 171, 191, 200, 209, 218, 225, 227, 252, 254, 261, 270, 317, 326, 344, 353, 360, 371, 387, 405, 416, 425, 504, 506, 515, 540, 605, 641, 684, 711, 720, 722, 731, 740, 767, 774, 801

Offset

1,2

Comments

A007953(n^2) = 2*A007953(n), sod(n^2) = 2*sod(n).

a(n) == {0 or 2} (mod 9). - Robert G. Wilson v, May 27 2009

Links

Zak Seidov, Table of n, a(n) for n=1..3001

Mathematica

fQ[n_] := Plus @@ IntegerDigits[n^2] == 2 Plus @@ IntegerDigits@n; Select[ Range[0, 809], fQ@# &] (* Robert G. Wilson v, May 27 2009 *)

Crossrefs

A007953 Digital sum (i.e., sum of digits) of n. A004159 Sum of digits of n^2.

Sequence in context: A103200 A067670 A217071 * A017185 A279774 A092595

Adjacent sequences: A159876 A159877 A159878 * A159880 A159881 A159882

Keyword

base,nonn

Author

Zak Seidov, Apr 25 2009

Extensions

Indices in b-file corrected by N. J. A. Sloane, Aug 31 2009

Status

approved