The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A037039 Least k such that 4*n*k+1 is a prime. 0
 1, 2, 1, 1, 2, 3, 1, 3, 1, 1, 2, 2, 1, 2, 1, 3, 2, 1, 3, 3, 4, 1, 3, 1, 1, 3, 1, 1, 2, 2, 3, 2, 3, 1, 2, 3, 1, 3, 1, 4, 5, 2, 1, 2, 1, 7, 5, 1, 1, 2, 2, 6, 5, 2, 3, 2, 1, 1, 3, 1, 3, 6, 3, 1, 2, 5, 1, 5, 1, 1, 2, 2, 1, 2, 2, 4, 2, 1, 1, 2, 4, 7, 3, 1, 3, 3, 1, 1, 3, 5, 3, 9, 1, 3, 2, 2, 1, 8, 1, 1, 2, 1, 3, 3, 1 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS EXAMPLE a(5)=2 because for n=5: 4*5*2+1=41 is a prime. PROG (PARI) a(n) = my(k = 0); while (! isprime(4*n*k+1), k++); k; \\ Michel Marcus, Sep 28 2013 CROSSREFS Cf. A016014. Sequence in context: A097868 A025830 A083796 * A182972 A153452 A090680 Adjacent sequences:  A037036 A037037 A037038 * A037040 A037041 A037042 KEYWORD nonn AUTHOR EXTENSIONS More terms from Erich Friedman STATUS approved

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

Last modified February 18 04:48 EST 2020. Contains 332011 sequences. (Running on oeis4.)