A002442 - OEIS

%I M3377 N1361 #32 Apr 22 2023 14:04:14

%S 1,4,10,17,27,40,54,71,100,121,144,170,207,237,270,314,351,400,441,

%T 484,540,587,647,710,764,831,1000,1061,1134,1210,1277,1357,1440,1524,

%U 1611,1700,1781,1874,2070,2167,2267,2370,2474,2581,2700,2811,3024,3140,3257

%N Squares written in base 9.

%D GCHQ, The GCHQ Puzzle Book, Penguin, 2016. See pages 108 and 300.

%D N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).

%D N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

%D V. Thébault, Les Récréations Mathématiques. Gauthier-Villars, Paris, 1952, p. 98.

%H Robert Israel, <a href="/A002442/b002442.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A007095(A000290(n)). - _Jason Kimberley_, Dec 13 2012

%p f:= proc(n) local L,i;

%p   L:= convert(n^2,base,9);

%p   add(L[i]*10^(i-1),i=1..nops(L))

%p end proc:

%p map(f, [$1..100]); # _Robert Israel_, Aug 12 2018

%t Table[FromDigits[IntegerDigits[n^2, 9]], {n, 1, 100}] (* _Stefan Steinerberger_, Apr 11 2006 *)

%o (Magma) [Seqint(Intseq(n^2, 9)): n in [1..60]]; // _Vincenzo Librandi_, Oct 16 2015

%o (PARI) a(n) = fromdigits(digits(n^2, 9)); \\ _Michel Marcus_, Aug 13 2018

%Y Cf. A000290, A007095.

%K nonn,base,easy

%O 1,2

%A _N. J. A. Sloane_

%E More terms from _Stefan Steinerberger_, Apr 11 2006