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A140590 Exchange successive pairs of terms of A000051. 2
3, 2, 9, 5, 33, 17, 129, 65, 513, 257, 2049, 1025, 8193, 4097, 32769, 16385, 131073, 65537, 524289, 262145, 2097153, 1048577, 8388609, 4194305, 33554433, 16777217, 134217729, 67108865, 536870913, 268435457, 2147483649, 1073741825, 8589934593, 4294967297, 34359738369 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Andrew Howroyd, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (1,4,-4).

FORMULA

From Andrew Howroyd, Jan 03 2020: (Start)

a(n) = 2^(n + (-1)^n) + 1.

a(n) = a(n-1) + 4*a(n-2) - 4*a(n-3) for n >= 3.

G.f.: (3 - x - 5*x^2)/((1 - x)*(1 - 2*x)*(1 + 2*x)). (End)

PROG

(PARI) a(n)={(1<<bitxor(n, 1)) + 1} \\ Andrew Howroyd, Jan 03 2020

(PARI) Vec((3 - x - 5*x^2)/((1 - x)*(1 - 2*x)*(1 + 2*x)) + O(x^40)) \\ Andrew Howroyd, Jan 03 2020

CROSSREFS

Cf. A000051.

Sequence in context: A231442 A319107 A228323 * A329211 A164279 A289053

Adjacent sequences:  A140587 A140588 A140589 * A140591 A140592 A140593

KEYWORD

nonn,easy

AUTHOR

Paul Curtz, Jul 06 2008

EXTENSIONS

Terms a(16) and beyond from Andrew Howroyd, Jan 03 2020

STATUS

approved

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Last modified October 20 19:28 EDT 2020. Contains 337909 sequences. (Running on oeis4.)