

A140505


Second differences of Jacobsthal sequence A001045, pairs with even and odd indices swapped.


2



2, 1, 4, 0, 12, 4, 44, 20, 172, 84, 684, 340, 2732, 1364, 10924, 5460, 43692, 21844, 174764, 87380, 699052, 349524, 2796204, 1398100, 11184812, 5592404, 44739244, 22369620, 178956972, 89478484, 715827884, 357913940, 2863311532, 1431655764, 11453246124
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OFFSET

0,1


COMMENTS

The second differences are 1, 2, 0, 4, 4, 12, 20, 44, ... (1)^(n+1)*A084247(n), essentially A097073, which are listed here with 1 <=> 2, 0 <=> 4 etc. swapped in pairs.


LINKS

Table of n, a(n) for n=0..34.


FORMULA

a(n) = 4*A092808(n2), n>1.
a(n+1)  2a(n) = (1)^n*A140504(n).
O.g.f.: (2+x5x^2)/[(1+x)(12x)(1+2x)].  R. J. Mathar, Jul 08 2008


CROSSREFS

Sequence in context: A077979 A122161 A067164 * A117971 A220420 A190616
Adjacent sequences: A140502 A140503 A140504 * A140506 A140507 A140508


KEYWORD

sign,less


AUTHOR

Paul Curtz, Jun 30 2008


EXTENSIONS

Edited by R. J. Mathar, Jul 08 2008


STATUS

approved



