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A198797
4*6^n-1.
1
3, 23, 143, 863, 5183, 31103, 186623, 1119743, 6718463, 40310783, 241864703, 1451188223, 8707129343, 52242776063, 313456656383, 1880739938303, 11284439629823, 67706637778943, 406239826673663, 2437438960041983, 14624633760251903
OFFSET
0,1
FORMULA
a(n) = 6*a(n-1)+5. a(n) = 7*a(n-1)-6*a(n-2), n>1.
G.f. ( 3+2*x ) / ( (6*x-1)*(x-1) ). - R. J. Mathar, Oct 30 2011
PROG
(Magma) [4*6^n-1: n in [0..30]]
CROSSREFS
Sequence in context: A179328 A255952 A089950 * A057835 A232145 A079755
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Oct 30 2011
STATUS
approved