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A071423 a(n) = a(n-1) + number of decimal digits of 2^n. Number of decimal digits of concatenation of first n powers of 2. 0
1, 2, 3, 5, 7, 9, 12, 15, 18, 22, 26, 30, 34, 39, 44, 49, 55, 61, 67, 74, 81, 88, 95, 103, 111, 119, 128, 137, 146, 156, 166, 176, 186, 197, 208, 219, 231, 243, 255, 268, 281, 294, 307, 321, 335, 349, 364, 379, 394, 410, 426, 442, 458, 475, 492, 509, 527, 545 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..58.

FORMULA

a(n) = a(n-1)+A034887(n). [R. J. Mathar, Sep 11 2009]

a(n) = 0.5 log 2/log 10 * n^2 + O(n)

MATHEMATICA

Do[s=s+Length[IntegerDigits[2^n]]; Print[s], {n, 1, 128}]

CROSSREFS

Cf. A058183.

Sequence in context: A279984 A184017 A024195 * A211004 A062781 A145919

Adjacent sequences:  A071420 A071421 A071422 * A071424 A071425 A071426

KEYWORD

easy,nonn,base

AUTHOR

Labos Elemer, May 27 2002

EXTENSIONS

An incorrect g.f. was deleted by N. J. A. Sloane, Sep 13 2009

Formula from Charles R Greathouse IV, Apr 28 2010

STATUS

approved

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Last modified October 21 20:44 EDT 2019. Contains 328315 sequences. (Running on oeis4.)