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1, 5, 11, 35, 71, 215, 431, 1295, 2591, 7775, 15551, 46655, 93311, 279935, 559871, 1679615, 3359231, 10077695, 20155391, 60466175, 120932351, 362797055, 725594111, 2176782335, 4353564671, 13060694015, 26121388031, 78364164095
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Interleaving of A164559 and A024062 without initial term 0.
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LINKS
| Vincenzo Librandi, Table of n, a(n) for n = 1..900
Index to sequences with linear recurrences with constant coefficients, signature (1,6,-6)
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FORMULA
| a(n) = 6*a(n-2)+5 for n > 2; a(1) = 1, a(2) = 5.
a(n) = (3-(-1)^n)*6^(1/4*(2*n-1+(-1)^n))/2-1.
G.f.: x*(1+4*x)/((1-x)*(1-6*x^2)).
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PROG
| (MAGMA) T:=[ n le 2 select 3*n-2 else 6*Self(n-2): n in [1..28] ]; [ n eq 1 select T[1] else Self(n-1)+T[n]: n in [1..#T]];
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CROSSREFS
| Cf. A164532, A164123 (partial sums of A162436), A164559 (6^n/3-1), A024062 (6^n-1).
a(n) = A026549(n)-1.
Sequence in context: A055936 A194589 A189918 * A054854 A188161 A005178
Adjacent sequences: A164557 A164558 A164559 * A164561 A164562 A164563
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KEYWORD
| nonn
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AUTHOR
| Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Aug 16 2009
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