A251608 Lexicographically earliest subsequence of the Fibonacci numbers (cf. A000045), such that gcd(a(n-2), a(n)) > 1 and gcd(a(n-1), a(n)) = 1.

2, 3, 8, 21, 34, 987, 2584, 6765, 10946, 75025, 196418, 9227465, 14930352, 7778742049, 20365011074, 225851433717, 365435296162, 10610209857723, 27777890035288, 72723460248141, 117669030460994, 3416454622906707, 8944394323791464, 23416728348467685

Offset

1,1

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

Example

   n |   a(n) | pos in A000045 | pos in A098550
  ---+--------+----------------+----------------
   1 |      2 |              3 |              2
   2 |      3 |              4 |              3
   3 |      8 |              6 |              6
   4 |     21 |              8 |             17
   5 |     34 |              9 |             35
   6 |    987 |             16 |            776
   7 |   2584 |             18 |           2755
   8 |   6765 |             20 |           5707
   9 |  10946 |             21 |          11652
  10 |  75025 |             25 |          66539

Prog

(Haskell)
a251608 n = a251608_list !! (n-1)
a251608_list = 2 : 3 : f 2 3 (drop 5 a000045_list) where
   f u v (w:ws) = if gcd u w > 1 && gcd v w == 1
                     then w : f v w ws else f u v ws

Crossrefs

Cf. A000045, A098550, A249357.

Sequence in context: A192151 A137652 A185381 * A288252 A122263 A132730

Adjacent sequences: A251605 A251606 A251607 * A251609 A251610 A251611

Keyword

nonn

Author

Reinhard Zumkeller, Dec 05 2014

Status

approved