

A084241


a(n) = 5*a(n1)4*a(n2) with n>1, a(0)=0, a(1)=1.


2



0, 1, 5, 21, 85, 341, 1365, 5461, 21845, 87381, 349525, 1398101, 5592405, 22369621, 89478485, 357913941, 1431655765, 5726623061, 22906492245, 91625968981, 366503875925, 1466015503701, 5864062014805, 23456248059221, 93824992236885
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OFFSET

0,3


COMMENTS

abs(a(n))=A002450(n)=A001045(2n).
Binomial transform is (0,1,3,9,27,...).


LINKS

Table of n, a(n) for n=0..24.
Index to sequences with linear recurrences with constant coefficients, signature (5,4).


FORMULA

a(n) = ((1)^n(4)^n)/3.
a(n) = sum(k=1..n, (1)^(n+k)*binomial(n, k)(3)^(k1)).
G.f.: x/((1+x)*(1+4*x)).
E.g.f.: (exp(x)exp(4x))/3.


CROSSREFS

Apart from signs, identical to A002450.
Cf. A084240.
Sequence in context: A246986 A247001 A028948 * A002450 A187063 A026855
Adjacent sequences: A084238 A084239 A084240 * A084242 A084243 A084244


KEYWORD

sign,easy


AUTHOR

Paul Barry, May 21 2003


STATUS

approved



