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A131787 a(n) = a(n-1) + (number of terms, from among the first (n-1) terms of the sequence, which are coprime to the n-th Fibonacci number). 1
1, 2, 3, 5, 8, 11, 17, 23, 28, 35, 45, 51, 63, 76, 83, 92, 108, 117, 135, 144, 156, 177, 199, 205, 224, 249, 264, 279, 307, 319, 349, 364, 385, 418, 443, 456, 492, 529, 553, 566, 606, 629, 671, 696, 713, 758, 804, 817, 862, 899, 929, 962, 1014, 1041, 1089, 1114 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..56.

EXAMPLE

The 6th Fibonacci number is 8. Of the first 5 terms, only terms a(1)=1, a(3)=3 and a(4) = 5 are coprime to 8. Since there are 3 such terms, a(6) = a(5) + 3 = 11.

MAPLE

with(combinat): a[1]:= 1: for n from 2 to 55 do ct := 0: for j to n-1 do if gcd(a[j], fibonacci(n)) = 1 then ct := ct+1 else ct := ct end if end do: a[n]:= a[n-1]+ct end do: seq(a[n], n = 1 .. 55); # Emeric Deutsch, Jul 24 2007

CROSSREFS

Cf. A131788.

Sequence in context: A039847 A046938 A060677 * A091498 A227562 A000511

Adjacent sequences:  A131784 A131785 A131786 * A131788 A131789 A131790

KEYWORD

nonn

AUTHOR

Leroy Quet, Jul 15 2007

EXTENSIONS

More terms from Joshua Zucker and Emeric Deutsch, Jul 18 2007

STATUS

approved

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Last modified August 4 16:34 EDT 2020. Contains 336202 sequences. (Running on oeis4.)