login
A088486
Primes p of the form k*(k + 1) - 1 such that p and p + 2 are twin primes.
3
5, 11, 29, 41, 71, 239, 419, 461, 599, 1481, 1721, 2549, 2969, 3539, 4421, 8009, 10301, 17291, 19181, 20021, 23561, 24179, 27059, 31151, 35531, 41411, 42641, 43889, 46439, 47741, 53591, 55931, 60761, 83231, 84389, 95789, 98909, 123551, 143261, 156419, 164429
OFFSET
1,1
COMMENTS
a(n) + 1 is an oblong number (A002378). - Michel Marcus, Feb 04 2017
LINKS
FORMULA
a(n) = A088485(n)*(A088485(n) + 1) - 1. - R. J. Mathar, Nov 14 2009
EXAMPLE
20*20 + 20 - 1 = 419, 419 and 421 twin primes, 419 is the 7th of the sequence for k = 20.
MATHEMATICA
Select[Table[k(k+1)-1, {k, 500}], AllTrue[#+{0, 2}, PrimeQ]&] (* Harvey P. Dale, Jul 08 2024 *)
CROSSREFS
Sequence in context: A141785 A144311 A074367 * A174917 A214451 A340544
KEYWORD
nonn
AUTHOR
Pierre CAMI, Nov 09 2003
EXTENSIONS
Sign in definition corrected by R. J. Mathar, Nov 13 2009
STATUS
approved