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A186078
Index of Fibonacci numbers having last digit greater than corresponding tribonacci number.
2
3, 11, 14, 16, 17, 21, 25, 26, 27, 29, 32, 33, 34, 35, 38, 39, 42, 43, 48, 49, 50, 52, 56, 57, 58, 63, 64, 65, 66, 70, 71, 74, 76, 78, 81, 83, 84, 87, 89, 91, 92, 94, 95, 96, 97, 98, 103, 107, 109, 110, 112, 118, 123, 125, 126, 127, 131, 132, 134, 136, 137
OFFSET
1,1
COMMENTS
Fib(a(n)) mod 10 > trib(a(n)) mod 10.
Precisely we have A000045(n) % 10 > A000213(n-1) % 10. - Michel Marcus, Jul 18 2013
Natural density 72/155, slightly higher than the 9/20 that would be expected with random sequences mod 10. - Charles R Greathouse IV, Jul 18 2013
FORMULA
a(n) = a(n-864) + 1860. - Charles R Greathouse IV, Jul 18 2013
EXAMPLE
a(5)=17 since Fib(17)=A000045(17)=1597 and trib(17)=A000213(16)=7473 and 7>3.
MATHEMATICA
nn = 250; Module[{f = Mod[Fibonacci[Range[nn]], 10], t = Mod[LinearRecurrence[{1, 1, 1}, {1, 1, 1}, nn], 10], ft}, ft = Thread[{f, t}]; Select[Range[nn], ft[[#, 1]] > ft[[#, 2]] &]] (* Harvey P. Dale, Dec 25 2012 *)
CROSSREFS
KEYWORD
nonn,base,easy,less
AUTHOR
Carmine Suriano, Feb 11 2011
STATUS
approved