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A028836 Iterated sum of digits of n is a power of 2. 2
1, 2, 4, 8, 10, 11, 13, 17, 19, 20, 22, 26, 28, 29, 31, 35, 37, 38, 40, 44, 46, 47, 49, 53, 55, 56, 58, 62, 64, 65, 67, 71, 73, 74, 76, 80, 82, 83, 85, 89, 91, 92, 94, 98, 100, 101, 103, 107, 109, 110, 112, 116, 118, 119, 121, 125, 127, 128, 130, 134, 136, 137, 139, 143, 145, 146, 148, 152, 154, 155 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..70.

FORMULA

Conjectures from Colin Barker, Feb 10 2020: (Start)

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

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

(End)

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

CROSSREFS

Cf. A010888, A028838, A028889.

Sequence in context: A247324 A043706 A296691 * A028838 A178332 A265155

Adjacent sequences:  A028833 A028834 A028835 * A028837 A028838 A028839

KEYWORD

nonn,base

AUTHOR

N. J. A. Sloane.

EXTENSIONS

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

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

STATUS

approved

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Last modified May 22 22:13 EDT 2022. Contains 353959 sequences. (Running on oeis4.)