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A032005 "AFK" (ordered, size, unlabeled) transform of 2,2,2,2,... 2
1, 2, 2, 10, 10, 18, 66, 74, 122, 178, 610, 666, 1146, 1586, 2450, 6778, 8026, 12738, 18258, 27194, 36938, 96226, 110578, 177930, 246474, 368354, 491426, 717418, 1543978, 1874418, 2855394, 3985322, 5765786, 7791250, 11066626, 14636538, 29870490, 35722514 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Number of compositions of n into distinct parts of 2 kinds. a(3) = 10: 3, 3', 21, 21', 2'1, 2'1', 12, 12', 1'2, 1'2'. - Alois P. Heinz, Sep 05 2015

LINKS

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

C. G. Bower, Transforms (2)

MAPLE

b:= proc(n, i, p) option remember;

      `if`(n=0, p!, `if`(i<1, 0, b(n, i-1, p)+

      `if`(i>n, 0, 2*b(n-i, i-1, p+1))))

    end:

a:= n-> b(n$2, 0):

seq(a(n), n=0..40);  # Alois P. Heinz, Sep 05 2015

CROSSREFS

a(n) = 2 * A032043(n) - 2 for n>0.

Sequence in context: A168295 A249152 A216708 * A147801 A263053 A066965

Adjacent sequences:  A032002 A032003 A032004 * A032006 A032007 A032008

KEYWORD

nonn

AUTHOR

Christian G. Bower

EXTENSIONS

a(0)=1 prepended by Alois P. Heinz, Sep 05 2015

STATUS

approved

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Last modified February 21 04:43 EST 2018. Contains 299389 sequences. (Running on oeis4.)