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!)
A099911 Primes of the form (p*(q-1) + (p-1)*q)/2, where p and q are consecutive odd primes. 3
11, 29, 131, 641, 1721, 2441, 3539, 10301, 22349, 36671, 70481, 79241, 170957, 175979, 186191, 198461, 212981, 304127, 313031, 324329, 434939, 655289, 777041, 852827, 1031231, 1126781, 1339781, 1511669, 1571237, 1741079, 1875521, 2003591 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
Or, primes of the form prime(n)*prime(n+1)- (prime(n)+prime(n+1))/2.
Subsequence of A099909.
LINKS
EXAMPLE
p=A000040(5)=11, q=A000040(5+1)=13: (11*(13-1)+(11-1)*13)/2 = (132+130)/2 = 131 = A000040(32), therefore 131 is a term.
MATHEMATICA
f[n_] := Block[{p = Prime[n], q = Prime[n + 1]}, r = (p*(q - 1) + (p - 1)*q)/2; If[ PrimeQ[r], r, 0]]; l = {}; Do[a = f[n]; If[a != 0, AppendTo[l, a]], {n, 300}]; l (* Robert G. Wilson v, Nov 02 2004 *)
Select[((#[[1]](#[[2]]-1))+((#[[1]]-1)#[[2]]))/2&/@Partition[ Prime[ Range[ 2, 300]], 2, 1], PrimeQ] (* Harvey P. Dale, Nov 28 2018 *)
CROSSREFS
Cf. A098142.
Sequence in context: A179502 A053703 A216559 * A118638 A088460 A168171
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Oct 29 2004
EXTENSIONS
More terms from Robert G. Wilson v, Nov 02 2004
Edited by N. J. A. Sloane at the suggestion of Andrew S. Plewe, May 21 2007
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 February 29 18:12 EST 2024. Contains 370428 sequences. (Running on oeis4.)