This site is supported by donations to The OEIS Foundation.

Annual Appeal: Today, Nov 11 2014, is the 4th anniversary of the launch of the new OEIS web site. 70,000 sequences have been added in these four years, all edited by volunteers. Please make a donation (tax deductible in the US) to help keep the OEIS running.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A165557 Primes of the form (p^2-1)/4-p where p are also primes. 2
 5, 19, 29, 71, 109, 181, 379, 419, 811, 1259, 1481, 2549, 2861, 3079, 4159, 4691, 7309, 8009, 8929, 13339, 17029, 18089, 19739, 21169, 23869, 24179, 27059, 35531, 37441, 39799, 41411, 43889, 46439, 47741, 48619, 53129, 59779, 61751, 67339, 89101, 93329 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS The associated primes p are in A165349. LINKS Vincenzo Librandi, Table of n, a(n) for n = 1..1000 EXAMPLE a(1) = 5 = (7^2-1)/4-7 generated by A165349(1)=7. a(2) = 19 = (11^2-1)/4-11 generated by A165349(2)=11. MATHEMATICA Select[Table[(p^2 - 1)/4 - p, {p, Prime[Range[200]]}], PrimeQ] (* Vincenzo Librandi, Oct 12 2012 *) PROG (MAGMA) [a: p in PrimesInInterval(5, 700) | IsPrime(a) where a is (p^2 - 1) div 4 - p ]; // Vincenzo Librandi, Oct 12 2012 CROSSREFS Cf. A165349. Sequence in context: A115103 A241043 A045457 * A138242 A163076 A122729 Adjacent sequences:  A165554 A165555 A165556 * A165558 A165559 A165560 KEYWORD nonn,easy AUTHOR Vincenzo Librandi, Sep 22 2009 EXTENSIONS Entries checked by R. J. Mathar, Sep 26 2009 STATUS approved

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

Content is available under The OEIS End-User License Agreement .