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!)
 A190052 Least number having exactly two odd prime factors that differ by 2*n^2. 3
 15, 33, 115, 185, 159, 553, 303, 393, 835, 2321, 7859, 1465, 3839, 1985, 3199, 5753, 13823, 3265, 3635, 8921, 4435, 2913, 3183, 12793, 37091, 40049, 19123, 4713, 18623, 19921, 21263, 10265, 64003, 67889, 41939, 44353, 8223, 84593, 21343, 9609, 37103, 17665 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Nathaniel Johnston, Table of n, a(n) for n = 1..10000 EXAMPLE a(11) = 7859 because 7859 = 29 * 271, and 271 - 29 = 242 = 2*11^2. MAPLE A190052 := proc(n) local k, p: k:=1: do p:=ithprime(k): if(isprime(p+2*n^2))then return p*(p+2*n^2): fi: k:=k+1: od: end: seq(A190052(n), n=1..50); # Nathaniel Johnston, May 04 2011 MATHEMATICA f[n_] := Block[{p = 3}, While[q=p+2*n^2; ! PrimeQ[q], p=NextPrime[p]]; p*q]; Table[ f[n], {n, 60}] CROSSREFS Sequence in context: A211327 A222179 A322493 * A242243 A219855 A270072 Adjacent sequences:  A190049 A190050 A190051 * A190053 A190054 A190055 KEYWORD nonn,easy AUTHOR Michel Lagneau, May 04 2011 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 May 12 07:28 EDT 2021. Contains 343821 sequences. (Running on oeis4.)