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A122770
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a(n) = numbers m such that 1+2m+3m^2=A056109(m) is a square.
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0
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0, 6, 88, 1230, 17136, 238678, 3324360, 46302366, 644908768, 8982420390, 125108976696, 1742543253358, 24270496570320, 338044408731126, 4708351225665448, 65578872750585150, 913395867282526656
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| All terms are even. Sequence is infinite. Corresponding squares are s^2 with s = 1,11,153,2131,29681,413403,5757961,80198051,1117014753,15558008491,216695104121,3018173449203,42037733184721.
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FORMULA
| a(n) = ((b+1)(7+4*b)^n - (b-1)(7-4*b)^n - 2)/6, b = sqrt(3); a(0) = 0, a(1) = 6, a(n) = 14*a(n-1) - a(n-2) + 4.
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CROSSREFS
| Cf. A056109.
Sequence in context: A171207 A173224 A178296 * A177567 A177563 A177569
Adjacent sequences: A122767 A122768 A122769 * A122771 A122772 A122773
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KEYWORD
| nonn
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AUTHOR
| Zak Seidov (zakseidov(AT)yahoo.com), Oct 21 2006
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