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A198688
6*7^n-1.
3
5, 41, 293, 2057, 14405, 100841, 705893, 4941257, 34588805, 242121641, 1694851493, 11863960457, 83047723205, 581334062441, 4069338437093, 28485369059657, 199397583417605, 1395783083923241, 9770481587462693, 68393371112238857
OFFSET
0,1
FORMULA
a(n) = 7*a(n-1)+6. a(n) = 8*a(n-1)-7*a(n-2), n>1.
G.f. ( 5+x ) / ( (7*x-1)*(x-1) ). - R. J. Mathar, Oct 30 2011
PROG
(Magma) [6*7^n-1: n in [0..30]]
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Vincenzo Librandi, Oct 29 2011
STATUS
approved