A049511 Numbers k such that prime(k) == 1 (mod 10).

5, 11, 13, 18, 20, 26, 32, 36, 42, 43, 47, 53, 54, 58, 60, 64, 67, 79, 82, 83, 89, 94, 98, 100, 105, 110, 115, 116, 121, 125, 126, 133, 135, 141, 142, 152, 156, 160, 164, 167, 172, 173, 177, 178, 182, 190, 193, 194, 197, 202, 210, 212, 216, 218, 221, 230, 233

Offset

1,1

Comments

Also k for which prime(k) == 1 (mod 5). - Bruno Berselli, Mar 04 2016

The asymptotic density of this sequence is 1/4 (by Dirichlet's theorem). - Amiram Eldar, Mar 01 2021

Links

Zak Seidov, Table of n, a(n) for n = 1..1000

Formula

a(n) = A000720(A030430(n)). - Ray Chandler, Nov 07 2006

Mathematica

Select[Range[210], Mod[Prime[ # ], 10] == 1 &] (* Ray Chandler, Nov 07 2006 *)

Prog

(Sage) [n for n in (1..300) if Mod(nth_prime(n), 10) == 1] # Bruno Berselli, Mar 04 2016
(PARI) isok(n) = !((prime(n)-1) % 10); \\ Michel Marcus, Mar 04 2016

Crossrefs

Cf. A000720, A024912, A030430, A081759.

Cf. A049508, A049509, A049510.

Sequence in context: A226614 A328058 A191042 * A024900 A087490 A140565

Adjacent sequences: A049508 A049509 A049510 * A049512 A049513 A049514

Keyword

nonn

Author

N. J. A. Sloane

Extensions

Extended by Ray Chandler, Nov 28 2003

Formula corrected by Zak Seidov, Sep 20 2011

Status

approved