A176914 List of pairs of primes p_i < p_j such that p_i*p_j = p_i + p_{i+1} + p_{i+2} + ... + p_j.

2, 5, 3, 13, 5, 31, 7, 53, 3536123, 128541727

Offset

1,1

Comments

First four pairs were found by F. Russo and the fifth by Philip Gibbs. It is not known whether other pairs exist.

References

A. Murphy, "Smarandache friendly numbers and a few more sequences", Smarandache Notions Journal, Vol. 12, 1-2-3, Spring 2001.

Links

Table of n, a(n) for n=1..10.

Philip Gibbs, A Fifth Smarandache Friendly Prime Pair

Felice Russo, On a problem concerning the Smarandache friendly prime pairs

Digital Library of Sciences

Example

(2, 5) is a pair because 2 and 5 are primes and 2*5 = 2 + 3 + 5. Similarly (3, 13) is a pair because 3 and 13 are primes and 3*13 = 3 + 5 + 7 + 11 + 13.

Crossrefs

Sequence in context: A279342 A169852 A318189 * A194010 A229609 A242171

Adjacent sequences: A176911 A176912 A176913 * A176915 A176916 A176917

Keyword

nonn,more

Author

G. Ornea (gornea2005(AT)gmail.com), Apr 28 2010

Extensions

Edited by N. J. A. Sloane, Jul 02 2017

Status

approved