%I #11 Feb 23 2020 15:31:32

%S 1,2,4,8,10,11,13,17,19,20,22,26,28,29,31,35,37,38,40,44,46,47,49,53,

%T 55,56,58,62,64,65,67,71,73,74,76,80,82,83,85,89,91,92,94,98,100,101,

%U 103,107,109,110,112,116,118,119,121,125,127,128,130,134,136,137,139,143,145,146,148,152,154,155

%N Iterated sum of digits of n is a power of 2.

%F Conjectures from _Colin Barker_, Feb 10 2020: (Start)

%F G.f.: x*(1 + x + 2*x^2 + 4*x^3 + x^4) / ((1 - x)^2*(1 + x)*(1 + x^2)).

%F a(n) = a(n-1) + a(n-4) - a(n-5) for n>5.

%F (End)

%F This g.f. follows from the observation that a(n+4) = a(n)+9 and this holds since the iterated sum of digits of N equals the iterated sum of digits of N+9. - _Peter Bala_, Feb 10 2020

%Y Cf. A010888, A028838, A028889.

%K nonn,base

%O 1,2

%A _N. J. A. Sloane_.

%E More terms from Scott Lindhurst (ScottL(AT)alumni.princeton.edu)

%E Checked by Neven Juric (neven.juric(AT)apis-it.hr), Feb 04 2008