A083518 Beginning with 3, a(i)*a(j) + 2 is prime for all i, j, i<>j.

3, 5, 7, 27, 45, 495, 3615, 16695, 533445, 832305, 122789427, 8705408757, 77597861913

Offset

1,1

Comments

All terms have the form 10*k+3, 10*k+5, or 10*k+7. [Corrected by Pontus von Brömssen, Oct 12 2023]

Conjecture: sequence is finite.

Next term is > 266*10^9. - David Wasserman, Nov 22 2004

Links

Table of n, a(n) for n=1..13.

Example

3*7+2, 5*7+2, 3*5+2, etc. are primes.

Crossrefs

Cf. A083519.

Sequence in context: A126670 A126669 A126668 * A352106 A061944 A288924

Adjacent sequences: A083515 A083516 A083517 * A083519 A083520 A083521

Keyword

nonn,more

Author

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 05 2003

Extensions

More terms from David Wasserman, Nov 22 2004

Status

approved