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A130667
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a(1) = 1; a(n) = max { 5*a(k)+a(n-k) | 1 <= k <= n/2 }, for n>1.
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3
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1, 6, 11, 36, 41, 66, 91, 216, 221, 246, 271, 396, 421, 546, 671, 1296, 1301, 1326, 1351, 1476, 1501, 1626, 1751, 2376, 2401, 2526, 2651, 3276, 3401, 4026, 4651, 7776, 7781, 7806, 7831, 7956, 7981, 8106, 8231, 8856, 8881, 9006, 9131, 9756, 9881, 10506, 11131
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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REFERENCES
| D. E. Knuth, Problem submitted to Amer. Math. Monthly, Jun 18 2007.
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FORMULA
| a(2n)=6a(n) and a(2n+1)=5a(n)+a(n+1).
Contribution from Gary W. Adamson (qntmpkt(AT)yahoo.com), Mar 26 2010: (Start)
Let r(x) = (1 + 6x + 5x^2). Then (1 + 6x + 11x^2 + 36x^3 + ...) =
r(x) * r(x^2) * r(x^4) * r(x^8) * ... (End)
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CROSSREFS
| Cf. A006046, A116520, A130665.
Sequence in context: A152987 A100093 A166702 * A108698 A002570 A038265
Adjacent sequences: A130664 A130665 A130666 * A130668 A130669 A130670
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KEYWORD
| nonn
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AUTHOR
| N. J. A. Sloane (njas(AT)research.att.com), based on a message from D. E. Knuth, Jun 23 2007
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