OFFSET
0,1
COMMENTS
Similar to A092474 except that a(n)+4m^2 is composite for m = n+1.
a(19)=163. All other terms after a(15) are greater than 10^17 (if they exist). [From Jens Kruse Andersen, Oct 24 2008]
LINKS
Carlos Rivera, Puzzle 464. p+4*x^2. [From Jens Kruse Andersen, Oct 24 2008]
EXAMPLE
a(3) = 277 because 277, 277 + 2^2 = 281, 277 + 4^2 = 293, and 277 + 6^2 = 313 are all prime, but 277 + 8^2 = 341 = 11*31 is composite, and there is no smaller prime with this property.
a(4) = 43: 43+4*1^2 = 47, which is prime. 43+4*2^2 = 59, which is prime. 43+4*3^2 = 79, which is prime. 43+4*4^2 = 107, which is prime. 43+4*5^2 = 143 = 11*13, which is composite.
CROSSREFS
KEYWORD
nonn
AUTHOR
Ray G. Opao, Mar 29 2004
EXTENSIONS
Correction and a(11) - a(15) from Jens Kruse Andersen, Oct 24 2008
Edited by N. J. A. Sloane, Feb 08 2019, merging this with an essentially identical sequence submitted by Jon E. Schoenfield, Feb 02 2019
STATUS
approved