A258340 a(n) = (7^n + 3^n - 2)/8.
1, 7, 46, 310, 2131, 14797, 103216, 721420, 5046661, 35316787, 247187986, 1730227330, 12111325591, 84778481977, 593446982356, 4154121702040, 29078830390921, 203551748166367, 1424862043454326, 9974033723049550, 69818234317954651, 488727634995505957
Offset: 1
Links
- Index entries for linear recurrences with constant coefficients, signature (11,-31,21).
Crossrefs
Cf. A074608.
Programs
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Magma
[(3^n+7^n-2)/8: n in [1..30]]; // Vincenzo Librandi, Aug 22 2015
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Mathematica
Table[(7^n + 3^n - 2)/8, {n, 1, 30}] (* Bruno Berselli, Aug 24 2015 *) LinearRecurrence[{11,-31,21},{1,7,46},30] (* Harvey P. Dale, May 01 2018 *) -
PARI
first(m)=vector(m,i,(3^i+7^i-2)/8) \\ Anders Hellström, Aug 20 2015
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Sage
[(7^n+3^n-2)/8 for n in (1..30)] # Bruno Berselli, Aug 24 2015
Formula
a(n) = (A074608(n) - 2)/8. - Michel Marcus, Aug 20 2015
G.f.: x*(1-4*x)/((1-x)*(1-3*x)*(1-7*x)). - Vincenzo Librandi, Aug 22 2015
a(n) = 11*a(n-1) - 31*a(n-2) + 21*a(n-3) with n>2, a(0)=0. - Bruno Berselli, Aug 24 2015
Comments