A131840 - OEIS

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A131840

Additive persistence of Cullen numbers.

0, 0, 1, 2, 1, 2, 2, 2, 3, 1, 2, 2, 2, 2, 2, 2, 2, 3, 3, 2, 2, 3, 2, 2, 2, 2, 3, 2, 3, 2, 2, 3, 3, 2, 2, 3, 3, 2, 2, 3, 2, 3, 3, 3, 3, 2, 3, 3, 2, 3, 3, 3, 3, 3, 3, 2, 3, 3, 3, 3, 3, 3, 3, 2, 3, 2, 2, 3, 2, 3, 3, 3, 3, 2, 2, 3, 2, 2, 2, 2, 3, 2, 2, 3, 2, 3, 3, 2

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OFFSET

1,4

LINKS

Table of n, a(n) for n=1..88.

EXAMPLE

Cullen number 385 --> 3+8+5=16 -->1+6=7 thus persistence is 2

MAPLE

with(numtheory): with(combinat): P:=proc(n) local a, t; t:=0; a:=n*2^n+1; while a>9 do t:=t+1; a:=convert(convert(a, base, 10), `+`); od; t;

end: seq(P(i), i=1..10^2);

CROSSREFS

Cf. A002064, A131837.