A139745 a(n) = 11^n - 7^n.
0, 4, 72, 988, 12240, 144244, 1653912, 18663628, 208594080, 2317594084, 25654949352, 283334343868, 3124587089520, 34425823133524, 379071610510392, 4172500607905708, 45916496933002560, 505214397985306564, 5558288899894321032, 61147691553229173148, 672670202666262397200
Offset: 0
Links
- Vincenzo Librandi, Table of n, a(n) for n = 0..300
- Index entries for linear recurrences with constant coefficients, signature (18,-77).
Programs
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Magma
[11^n-7^n: n in [0..30]]; // Vincenzo Librandi, Jun 02 2011
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Mathematica
Table[11^n-7^n,{n,0,30}] (* or *) LinearRecurrence[{18,-77},{0,4},30] (* Harvey P. Dale, Jun 17 2014 *)
Formula
a(n) = 18*a(n-1) - 77*a(n-2). - Vincenzo Librandi, Jun 02 2011
From Stefano Spezia, Mar 09 2025: (Start)
G.f.: 4*x/((1 - 11*x)*(1 - 7*x)).
E.g.f.: exp(7*x)*(exp(4*x) - 1). (End)
a(n) = 4*A016183(n-1) for n >= 1. - Elmo R. Oliveira, Apr 01 2025