

A176662


a(0)=2, a(1)=7, and a(n) = (3*n+1)*2^(n1) if n > 1.


2



2, 7, 14, 40, 104, 256, 608, 1408, 3200, 7168, 15872, 34816, 75776, 163840, 352256, 753664, 1605632, 3407872, 7208960, 15204352, 31981568, 67108864, 140509184, 293601280, 612368384, 1275068416, 2650800128, 5502926848, 11408506880, 23622320128, 48855252992
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OFFSET

0,1


COMMENTS

The sequence appears on the main diagonal of the array defined by A123167 in the first row and successive differences in followup rows:
2, 3, 10, 7, 18, 11, 26, 15, 34, 19, ... A123167
1, 7, 3, 11, 7, 15, 11, 19, 15, 23, ... first diff
6, 10, 14, 18, 22 26, 30, 34, 38, ... second diff
16, 24, 32, 40, 48, 56, 64, 72, 80, ... third diff


LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (4,4).


FORMULA

a(n) mod 9 = A010710(n1), n > 2.
a(2n) + a(2n+1) = 9, 54, 360, 2016, ...
a(n)  2*a(n1) = 12*A131577(n2), n > 1.
a(n) = 4*a(n1)  4*a(n2), n > 3.
G.f.: (6*x^2+12*x^3+2x)/(12*x)^2.


MATHEMATICA

LinearRecurrence[{4, 4}, {2, 7, 14, 40}, 40] (* or *) Join[{2, 7}, Table[ (3n+1) 2^(n1), {n, 2, 40}]] (* Harvey P. Dale, Oct 05 2019 *)


CROSSREFS

Sequence in context: A194590 A107373 A336579 * A018526 A329115 A018542
Adjacent sequences: A176659 A176660 A176661 * A176663 A176664 A176665


KEYWORD

nonn,easy


AUTHOR

Paul Curtz, Apr 23 2010


EXTENSIONS

Edited by R. J. Mathar, Jun 30 2010


STATUS

approved



