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Search: id:A068293
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| A068293 |
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1/4 the number of colorings of an n X n octagonal array with 4 colors. |
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+0
2
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| 1, 6, 18, 42, 90, 186, 378, 762, 1530, 3066, 6138, 12282, 24570, 49146, 98298, 196602, 393210, 786426, 1572858, 3145722, 6291450, 12582906, 25165818, 50331642, 100663290, 201326586, 402653178, 805306362, 1610612730
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Contribution from Gary W. Adamson (qntmpkt(AT)yahoo.com), Jan 13 2009: (Start)
Equals inverse binomial transform of A091344: (1, 7, 31, 115, 391,...)
and binomial transform of (1, 5, 7, 5, 7, 5,...). (End)
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FORMULA
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G.f.: (1+x)*(1+2*x)/(1-x)/(1-2*x) - Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 13 2002
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MATHEMATICA
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a=0; lst={1}; k=6; Do[a+=k; AppendTo[lst, a]; k+=k, {n, 0, 5!}]; lst [From Vladimir Orlovsky (4vladimir(AT)gmail.com), Dec 16 2008]
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PROGRAM
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(PARI) a(n)=polcoeff(prod(i=1, 2, (1+i*x))/(prod(i=1, 2, (1-i*x))+x*O(x^n)), n) for(n=0, 50, print1(a(n), ", "))
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CROSSREFS
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Cf. A068239-A068305, A000332, A002417, A027441.
A091344 [From Gary W. Adamson (qntmpkt(AT)yahoo.com), Jan 13 2009]
Sequence in context: A015942 A009945 A011930 this_sequence A009957 A011929 A070735
Adjacent sequences: A068290 A068291 A068292 this_sequence A068294 A068295 A068296
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KEYWORD
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nonn
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AUTHOR
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Ron Hardin (rhhardin(AT)att.net), Feb 24 2002
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EXTENSIONS
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More terms from Benoit Cloitre (benoit7848c(AT)orange.fr), Apr 13 2002
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