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1,2

n={1, 2, 4, 10, 26} yields primes p(n)={2, 3, 7, 29, 101}. There are no more such n up to n=100. Verified by Ray Chandler.

Table of n, a(n) for n=1..5.

J. V. Post, Math Pages.

Numbers n such that (prime(n)-1)! + prime(n)^2 is prime, where prime(n) is the n-th prime.

a(3) = 4 because (prime(4)-1)! + prime(4)^2 = (7-1)! + 7^2 = 720 + 49 = 769

is prime and is the 3rd such prime of that form.

Cf. A100858.

Sequence in context: A085633 A111564 A007021 * A247395 A183947 A154322

Adjacent sequences: A100602 A100603 A100604 * A100606 A100607 A100608

nonn

Jonathan Vos Post, Nov 30 2004

approved