A045453 Primes congruent to {0, 1} mod 5.
5, 11, 31, 41, 61, 71, 101, 131, 151, 181, 191, 211, 241, 251, 271, 281, 311, 331, 401, 421, 431, 461, 491, 521, 541, 571, 601, 631, 641, 661, 691, 701, 751, 761, 811, 821, 881, 911, 941, 971, 991, 1021, 1031, 1051, 1061, 1091, 1151, 1171, 1181, 1201, 1231
Offset: 1
Examples
a(1) = 5 is the first primes that is congruent to 0 or 1, modulo 5. a(2) = 11 is the first prime congruent to 1 modulo 5, and therefore (since there is no other prime congruent to 0 mod 5) the second term of this sequence. a(10^k) = (181, 2791, 38201, 479771, 5803381, 67881871, 776580131, ...) for k = 1, 2, 3, ...
Links
- Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Crossrefs
Programs
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Magma
[ p: p in PrimesUpTo(1300) | p mod 5 in {0, 1} ]; // Vincenzo Librandi, Aug 13 2012 -
Mathematica
Select[Prime@Range[210], MemberQ[{0, 1}, Mod[ #, 5]] &] (* Ray Chandler, Dec 06 2006 *) -
PARI
A045453_vec(Nmax)=select( p->p%5<2, primes([1,Nmax])) \\ or: A045453(n)=forprime(p=1,,p%5>1||n--||return(p)) \\ M. F. Hasler, Jan 15 2018
Formula
a(n) = A030430(n-1) for all n >= 2. - M. F. Hasler, Jan 15 2018
Extensions
Extended by Ray Chandler, Nov 28 2003
Checked by Neven Juric (neven.juric(AT)apis-it.hr), Feb 04 2008
Edited and a(1000) double checked by M. F. Hasler, Jan 15 2018
Comments