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A098156
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Interleave n+1 and 2n+1 and take binomial transform.
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4
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1, 2, 5, 13, 32, 76, 176, 400, 896, 1984, 4352, 9472, 20480, 44032, 94208, 200704, 425984, 901120, 1900544, 3997696, 8388608, 17563648, 36700160, 76546048, 159383552, 331350016, 687865856, 1426063360, 2952790016, 6106906624
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| Binomial transform of A029579.
Contribution from Johannes W. Meijer (meijgia(AT)hotmail.com), Aug 15 2010: (Start)
An elephant sequence, see A175655. For the central square 16 A[5] vectors, with decimal values between 59 and 440, lead to this sequence (without a(1)). For the corner squares these vectors lead to the companion sequence A066373 (with a leading 1 added).
(End)
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FORMULA
| G.f. : (1-2x+x^2+x^3)/(1-2x)^2; a(n)=0^n/2+sum{k=0..n, binomial(-1)^(n-k)*k)}/4+2^n/2+3n*2^(n-1)/4; a(n)=sum{j=0..n, sum{k=0..n, binomial(n, 2(k-j)}}.
a(n)=sum{k=0..n, sum{i=0..k, C(n, 2i)}} - Paul Barry (pbarry(AT)wit.ie), Jan 13 2005
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CROSSREFS
| Sequence in context: A086758 A179257 A116702 * A098586 A199812 A110320
Adjacent sequences: A098153 A098154 A098155 * A098157 A098158 A098159
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KEYWORD
| easy,nonn
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AUTHOR
| Paul Barry (pbarry(AT)wit.ie), Aug 29 2004
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