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A164737
a(n) = 8*a(n-2) for n > 2; a(1) = 5, a(2) = 12.
5
5, 12, 40, 96, 320, 768, 2560, 6144, 20480, 49152, 163840, 393216, 1310720, 3145728, 10485760, 25165824, 83886080, 201326592, 671088640, 1610612736, 5368709120, 12884901888, 42949672960, 103079215104, 343597383680, 824633720832
OFFSET
1,1
COMMENTS
Interleaving of 5*A001018 and 12*A001018.
Binomial transform is A096980 without initial terms 1. Second binomial transform is A164593. Third binomial transform is A101386.
FORMULA
a(n) = (13 - 7*(-1)^n)*2^(1/4*(6*n - 11 + 3*(-1)^n)).
G.f.: x*(5 + 12*x)/(1 - 8*x^2).
MAPLE
seq(coeff(series( x*(5+12*x)/(1-8*x^2) , x, n+1), x, n), n=1..30); # G. C. Greubel, Apr 16 2020
MATHEMATICA
LinearRecurrence[{0, 8}, {5, 12}, 30] (* G. C. Greubel, Apr 16 2020 *)
PROG
(Magma) [ n le 2 select 7*n-2 else 8*Self(n-2): n in [1..26] ];
(Sage) [(13 -7*(-1)^n)*2^((6*n -11 +3*(-1)^n)/4) for n in (1..30)] # G. C. Greubel, Apr 16 2020
CROSSREFS
Cf. A001018 (powers of 8), A067412, A096980, A101386, A164593.
Sequence in context: A233007 A221795 A092772 * A120779 A082189 A129795
KEYWORD
nonn
AUTHOR
Klaus Brockhaus, Aug 24 2009
STATUS
approved