A239367 The bisection of A238315 that remains constant with changes in the offset of the exponent of the second term.

1, 5, 13, 29, 69, 197, 669, 2509, 9813, 38965, 155501, 621565, 2485733, 9942309, 39768509, 159073197, 636291829, 2545166229, 10180663693, 40722653405, 162890612101, 651562446725, 2606249785053, 10424999138189

Offset

1,2

Comments

Last digits repeat {1,5,3,9,9,7,9,9,3,5}

Links

Table of n, a(n) for n=1..24.

Formula

Conjectures from Colin Barker, Dec 30 2014: (Start)

a(n) = (-1+4^n-12*n+36*n^2)/27.

a(n) = 6*a(n-1)-8*a(n-2)-2*a(n-3)+9*a(n-4)-4*a(n-5).

G.f.: -x*(7*x^2+2*x-1) / ((x-1)^3*(4*x-1)).

(End)

Crossrefs

Cf. A238315.

Sequence in context: A099970 A073857 A295112 * A124698 A337761 A147278

Adjacent sequences: A239364 A239365 A239366 * A239368 A239369 A239370

Keyword

nonn

Author

Richard R. Forberg, Mar 30 2014

Status

approved