login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A176983 Primes p such that smallest prime q > p^2 is of form q = p^2 + k^2. 5
2, 5, 7, 13, 17, 37, 47, 67, 73, 97, 103, 137, 163, 167, 193, 233, 277, 281, 293, 307, 313, 317, 347, 373, 389, 421, 439, 461, 463, 487, 499, 503, 547, 571, 577, 593, 607, 613, 661, 677, 691, 701, 739, 743, 769, 787, 821, 823, 827, 829, 853, 883, 953, 967, 983 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
By Fermat's 4n+1 theorem, q must be congruent to 1 (mod 4).
Corresponding values of k: 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 4, 2, 2, 2, 2, 2, 2, 4, 4, 4, 6, 2, 2, 4, 2. - Zak Seidov, Nov 04 2013
LINKS
Eric W. Weisstein, Fermat's 4n+1 Theorem
EXAMPLE
17 is here because 293 is the first prime after 17^2 and 293 = 17^2 + 2^2.
MATHEMATICA
Select[Prime[Range[200]], IntegerQ[Sqrt[NextPrime[ #^2] - #^2]] & ]
CROSSREFS
A062324 is subsequence. - Zak Seidov, Nov 04 2013
Sequence in context: A260388 A169586 A023229 * A160676 A169690 A144300
KEYWORD
nonn
AUTHOR
Ulrich Krug (leuchtfeuer37(AT)gmx.de), Apr 30 2010
EXTENSIONS
Edited and extended by T. D. Noe, May 12 2010
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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified July 17 13:26 EDT 2024. Contains 374377 sequences. (Running on oeis4.)