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

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A244520 a(n) = A080715(n+1) / 2. 2
 1, 3, 5, 11, 15, 21, 29, 35, 39, 41, 51, 65, 95, 105, 155, 165, 179, 191, 221, 231, 239, 281, 329, 371, 419, 431, 485, 519, 611, 641, 659, 809, 905, 935, 989, 1019, 1031, 1049, 1121, 1199, 1229, 1289, 1451, 1469, 1481, 1509, 1541, 1661, 1821, 1931, 2109, 2129, 2141, 2339, 2549, 2795, 2969, 3021, 3039, 3189, 3299, 3329 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Numbers k such that 2d + k/d is prime for every d|k. Such k must be an odd squarefree number. Primes in the sequence are A045536. - Thomas Ordowski, Nov 16 2017 LINKS Alois P. Heinz, Table of n, a(n) for n = 1..1000 FORMULA A088627(a(n)) = A000005(a(n)) = 2^m. - Thomas Ordowski, Nov 16 2017 MATHEMATICA Select[Range[1, 3400, 2], Function[n, AllTrue[Divisors@ n, PrimeQ[2 # + n/#] &]]] (* Michael De Vlieger, Nov 18 2017 *) PROG (PARI) is_ok(n)=n=2*n; fordiv(n, d, if(!isprime(d+n/d), return(0))); return(1); for(n=1, 10^4, if(is_ok(n), print1(n, ", "))); CROSSREFS Cf. A045536, A080715, A088627. Sequence in context: A265121 A281575 A105772 * A034169 A217384 A335279 Adjacent sequences: A244517 A244518 A244519 * A244521 A244522 A244523 KEYWORD nonn AUTHOR Joerg Arndt, Jul 10 2014 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.

Last modified January 30 05:43 EST 2023. Contains 359939 sequences. (Running on oeis4.)