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A090562 Primes of the form 5k^2 + 5k + 1. 16
11, 31, 61, 101, 151, 211, 281, 661, 911, 1051, 1201, 1361, 1531, 1901, 2311, 2531, 3001, 3251, 3511, 4651, 5281, 6301, 6661, 7411, 9461, 9901, 12251, 13781, 14851, 15401, 18301, 18911, 19531, 20161, 22111, 24151, 24851, 25561, 27011, 27751 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Or, primes obtained as a concatenation of a triangular number and 1.
Centered decagonal primes. - Paul Muljadi, Oct 04 2005
LINKS
MATHEMATICA
Select[5(#^2 - #) + 1 & /@ Range[75], PrimeQ[ # ] &] (* Robert G. Wilson v, Oct 10 2005 *)
PROG
(Magma) [a: n in [0..100] | IsPrime(a) where a is 5*n^2 + 5*n + 1]; // Vincenzo Librandi, Dec 13 2011
CROSSREFS
Sequence in context: A202007 A125239 A062786 * A174244 A136061 A296034
KEYWORD
easy,nonn
AUTHOR
Amarnath Murthy, Dec 11 2003
EXTENSIONS
Edited and extended by Robert G. Wilson v, Oct 10 2005
STATUS
approved

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Last modified June 17 15:57 EDT 2024. Contains 373463 sequences. (Running on oeis4.)