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A235684 Number of compositions of n into powers of 3 and doubled powers of 3. 3
1, 1, 2, 4, 7, 13, 25, 46, 86, 162, 302, 565, 1058, 1978, 3700, 6923, 12949, 24223, 45316, 84769, 158575, 296645, 554923, 1038079, 1941911, 3632677, 6795551, 12712263, 23780486, 44485521, 83217888, 155673480, 291214232, 544766722, 1019080592, 1906366927 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

a(n+1)/a(n) tends to 1.87067337504749000600807516613083316430149226... (used Richardson's extrapolation) - Vaclav Kotesovec, Jan 14 2014

LINKS

Alois P. Heinz, Table of n, a(n) for n = 0..1000

EXAMPLE

a(3) = 4: 1+1+1, 2+1, 1+2, 3, thus we have 4 compositions with the allowed parts.

MAPLE

a:= proc(n) option remember; `if`(n=0, 1, `if`(n<0, 0,

      add(a(n-3^i)+a(n-2*3^i), i=0..ilog[3](n))))

    end:

seq(a(n), n=0..40);  # Alois P. Heinz, Jan 13 2014

CROSSREFS

Cf. A078932, A235669, A235773.

Sequence in context: A000074 A079958 A224341 * A018082 A018083 A108361

Adjacent sequences:  A235681 A235682 A235683 * A235685 A235686 A235687

KEYWORD

nonn

AUTHOR

Vladimir Shevelev and Peter J. C. Moses, Jan 13 2014

STATUS

approved

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Last modified February 20 18:30 EST 2020. Contains 332082 sequences. (Running on oeis4.)