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Search: id:A152968
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| 1, 2, 2, 2, 4, 6, 4, 2, 4, 6, 6, 8, 14, 16, 8, 2, 4, 6, 6, 8, 14, 16, 10, 8, 14, 18, 20, 30, 44, 40, 16, 2, 4, 6, 6, 8, 14, 16, 10, 8, 14, 18, 20, 30, 44, 40, 18, 8, 14, 18, 20, 30, 44, 42, 28, 30, 46, 56, 70, 104, 128, 96, 32, 2
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Also, first differences of toothpicks numbers A152998. [From Omar E. Pol (info(AT)polprimos.com), Jan 02 2009]
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FORMULA
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Write n = 2^i +j, 0 <= j < 2^i; then a(n) = Sum_k 2^(wt(j+k)-k)*binomial(wt(j+k),k). except that a(2^r-1) = 2^(r-1). - N. J. A. Sloane, Jun 03 2009, Jul 16 2009
G.f.: x*(Prod(1+x^(2^k-1)+2*x^(2^k),k=0..oo)-1)/(1+2*x). - N. J. A. Sloane, Jun 05 2009
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EXAMPLE
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Triangle begins:
.1;
.2,2;
.2,4,6,4;
.2,4,6,6,8,14,16,8;
.2,4,6,6,8,14,16,10,8,14,18,20,30,44,40,16;
....
Rows approach A151688. - N. J. A. Sloane, Jun 03 2009
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CROSSREFS
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Cf. A139250, A139251, A139252, A152978, A152980, A153006, A152998.
Sequence in context: A024405 A082547 A068928 this_sequence A147599 A086420 A103265
Adjacent sequences: A152965 A152966 A152967 this_sequence A152969 A152970 A152971
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KEYWORD
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more,nonn
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AUTHOR
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Omar E. Pol (info(AT)polprimos.com), Dec 16 2008, Dec 20 2008
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