The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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 Vincenzo Librandi, Table of n, a(n) for n = 1..5000 Wikipedia, Centered decagonal number. 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 Cf. A090563, A062786. Sequence in context: A202007 A125239 A062786 * A174244 A136061 A296034 Adjacent sequences: A090559 A090560 A090561 * A090563 A090564 A090565 KEYWORD easy,nonn AUTHOR Amarnath Murthy, Dec 11 2003 EXTENSIONS Edited and extended by Robert G. Wilson v, Oct 10 2005 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

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