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A216561 Numbers n such that the n-th Fibonacci number is prime, but cannot be written in the form a^2 + 5*b^2. 0
3, 4, 5, 7, 13, 17, 23, 43, 47, 83, 137, 433, 4723, 5387, 9677, 30757, 50833, 201107, 931517, 1049897, 1285607, 1636007 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..22.

Blair Kelly, Factorizations of Fibonacci and Lucas numbers

CROSSREFS

Cf. A000045, A001605.

Sequence in context: A325422 A190213 A216574 * A192269 A284618 A101759

Adjacent sequences:  A216558 A216559 A216560 * A216562 A216563 A216564

KEYWORD

nonn

AUTHOR

V. Raman, Sep 08 2012

STATUS

approved

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Last modified August 4 12:27 EDT 2021. Contains 346447 sequences. (Running on oeis4.)