A074855 Primes p such that all p-t for p/2 < t < p are nonprime, where t is a triangular number.

2, 3, 7, 19, 29, 37, 61, 211, 521, 613, 1579, 2131, 2467, 2551, 3331

Offset

1,1

Comments

Next term, if it exists, is greater than 15900000. (Is this sequence finite?) - Ryan Propper, May 20 2006

If it exists, a(16) > 5001022933. - Sean A. Irvine, Jan 31 2025

Links

Table of n, a(n) for n=1..15.

Example

29 is in the sequence because the triangular numbers between 14 and 29 are 15, 21, 28 and 29-15 = 14, 29-21 = 8, 29-28 = 1 are all composite.
7 is in the sequence because the only triangular number between 7/2 and 7 is 6 and 7-6 = 1 is not prime. - Sean A. Irvine, Jan 31 2025

Crossrefs

Sequence in context: A038878 A040112 A246373 * A038935 A214627 A354215

Adjacent sequences: A074852 A074853 A074854 * A074856 A074857 A074858

Keyword

more,nonn

Author

Jason Earls, Sep 11 2002

Extensions

Name corrected by Sean A. Irvine, Jan 31 2025

Status

approved