A121390 - OEIS

A121390

Sequence generated by the recurrence below begins with exactly seven primes.

2, 8607769, 25823309, 222281113118699, 5740034091209256896999, 1275901167133279185594625154673899999, 7323716196358702385046852882006552347670105360888299999999

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OFFSET

0,1

COMMENTS

This sequence has the smallest value of a(1) for a(0) = 2 and this recurrence such that the first seven terms are primes. The first composite term is too large to include. Note also that each a(n) has Fibonacci(n) trailing 9's (see A121389).

LINKS

Table of n, a(n) for n=0..6.

FORMULA

a(0) = 2; a(1) = 8607769; a(n) = a(n-2)*a(n-1) + a(n-2) + a(n-1).

EXAMPLE

a(2) = 25823309 = 2*8607769 + 2 + 8607769 and is prime.

CROSSREFS

Cf. A000045, A063896, A121389.

Sequence in context: A233555 A273729 A324440 * A170997 A326615 A259407

Adjacent sequences: A121387 A121388 A121389 * A121391 A121392 A121393

KEYWORD

nonn

AUTHOR

Rick L. Shepherd, Jul 26 2006

STATUS

approved