

A074878


Row sums of triangle in A074829.


7



1, 2, 6, 14, 32, 70, 150, 316, 658, 1358, 2784, 5678, 11534, 23356, 47178, 95110, 191440, 384854, 772902, 1550972, 3110306, 6234142, 12490176, 25015774, 50088862, 100270460, 200690970, 401624726, 803642288, 1607920198, 3216868854, 6435401788, 12873496114, 25751348846
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OFFSET

1,2


COMMENTS

An elephant sequence, see A175654. For the corner squares 16 A[5] vectors, with decimal values between 43 and 424, lead to this sequence. For the central square these vectors lead to the companion sequence A175657.  Johannes W. Meijer, Aug 15 2010


LINKS

G. C. Greubel, Table of n, a(n) for n = 1..1000
Index entries for linear recurrences with constant coefficients, signature (3,1,2).


FORMULA

From Philippe Deléham, Sep 20 2006: (Start)
a(1)=1, a(2)=2, a(3)=6, a(n) = 3*a(n1)  a(n2)  2*a(n3) for n>3.
a(n) = 3*2^(n1)  2*F(n+1), F(n)=A000045(n).
G.f.: x*(1x+x^2)/(13*x+x^2+2*x^3). (End)
a(1)=1, a(n) = 2*(a(n1) + F(n2)) where the Fibonacci number F(n2) = A000045(n2).  Anton Vrba (antonvrba(AT)yahoo.com), Feb 06 2007
a(n) = 3*2^n  2*F(n+2), with offset 0 and F(n)=A000045(n).  Johannes W. Meijer, Aug 15 2010


MATHEMATICA

Table[3*2^(n1)  2*Fibonacci[n+1], {n, 1, 40}] (* G. C. Greubel, Jul 12 2019 *)


PROG

(PARI) vector(40, n, 3*2^(n1) 2*fibonacci(n+1)) \\ G. C. Greubel, Jul 12 2019
(MAGMA) [3*2^(n1)  2*Fibonacci(n+1): n in [1..40]]; // G. C. Greubel, Jul 12 2019
(Sage) [3*2^(n1)  2*fibonacci(n+1) for n in (1..40)] # G. C. Greubel, Jul 12 2019
(GAP) List([1..40], n> 3*2^(n1)  2*Fibonacci(n+1)); # G. C. Greubel, Jul 12 2019


CROSSREFS

Cf. A000045.
Sequence in context: A217941 A232434 A096238 * A065495 A131352 A232230
Adjacent sequences: A074875 A074876 A074877 * A074879 A074880 A074881


KEYWORD

easy,nonn


AUTHOR

Joseph L. Pe, Sep 30 2002


EXTENSIONS

More terms from Philippe Deléham, Sep 20 2006
Terms a(23) onward added by G. C. Greubel, Jul 12 2019


STATUS

approved



