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a(n) is the cube of the sum of digits of n.
3

%I #16 Aug 15 2024 11:55:36

%S 0,1,8,27,64,125,216,343,512,729,1,8,27,64,125,216,343,512,729,1000,8,

%T 27,64,125,216,343,512,729,1000,1331,27,64,125,216,343,512,729,1000,

%U 1331,1728,64,125,216,343,512,729,1000,1331,1728,2197,125,216,343,512

%N a(n) is the cube of the sum of digits of n.

%F a(n) = (A007953(n))^3. - _R. J. Mathar_, Apr 22 2010

%e Trajectories of x->a(x), see A182128:

%e 1 ->1 ->1 ->1 ->1 ->1 ->1 ->1 ->1 ->...

%e 2 ->8 ->512 ->512 ->512 ->512 ->512 ->512 ->512 ->...

%e 3 ->27 ->729 ->5832 ->5832 ->5832 ->5832 ->5832 ->5832 ->...

%e 4 ->64 ->1000 ->1 ->1 ->1 ->1 ->1 ->1 ->...

%e 5 ->125 ->512 ->512 ->512 ->512 ->512 ->512 ->512 ->...

%e 6 ->216 ->729 ->5832 ->5832 ->5832 ->5832 ->5832 ->5832 ->...

%e 7 ->343 ->1000 ->1 ->1 ->1 ->1 ->1 ->1 ->...

%e 8 ->512 ->512 ->512 ->512 ->512 ->512 ->512 ->512 ->...

%e 9 ->729 ->5832 ->5832 ->5832 ->5832 ->5832 ->5832 ->5832 ->...

%e 10 ->1 ->1 ->1 ->1 ->1 ->1 ->1 ->1 ->...

%e 11 ->8 ->512 ->512 ->512 ->512 ->512 ->512 ->512 ->...

%e 12 ->27 ->729 ->5832 ->5832 ->5832 ->5832 ->5832 ->5832 ->...

%e 13 ->64 ->1000 ->1 ->1 ->1 ->1 ->1 ->1 ->...

%e 14 ->125 ->512 ->512 ->512 ->512 ->512 ->512 ->512 ->...

%e - _R. J. Mathar_, Jul 08 2012

%t a[n_]:=DigitSum[n]^3; Array[a,54,0] (* _Stefano Spezia_, Aug 15 2024 *)

%o (Python)

%o def a(n): return sum(map(int, str(n)))**3

%o print([a(n) for n in range(54)]) # _Michael S. Branicky_, Dec 26 2021

%Y Cf. A007953, A182128.

%K base,easy,nonn

%O 0,3

%A _Giovanni Teofilatto_, May 25 2006

%E Name and offset corrected by _Jon E. Schoenfield_, Dec 26 2021