A175443 a(1)=2, a(n+1) = smallest prime > a(n) such that a(n+1)+a(n) is multiple of 5.

2, 3, 7, 13, 17, 23, 37, 43, 47, 53, 67, 73, 97, 103, 107, 113, 127, 163, 167, 173, 197, 223, 227, 233, 257, 263, 277, 283, 307, 313, 317, 353, 367, 373, 397, 433, 457, 463, 467, 503, 547, 563, 577, 593, 607, 613, 617, 643, 647, 653, 677, 683, 727, 733, 757

Offset

1,1

Comments

Lexicographically first subsequence of primes such that the sum of any two adjacent terms is a multiple of 5. - Charles R Greathouse IV, Apr 13 2015

For n >= 1, a(2*n) == 3 (mod 10) and a(2*n+1) == 7 (mod 10). - Robert Israel, Apr 13 2015

Links

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

Maple

a[1]:= 2: a[2]:= 3:
for n from 2 to 99 do
for t from a[n]+ (-2*a[n] mod 10) by 10 while not isprime(t) do od:
a[n+1]:= t;
od:
seq(a[n], n=1..100); # Robert Israel, Apr 13 2015

Mathematica

spm5[n_]:=Module[{p=NextPrime[n]}, While[!Divisible[n+p, 5], p = NextPrime[ p]]; p]; NestList[spm5, 2, 60] (* Harvey P. Dale, Jan 02 2017 *)

Prog

(PARI) list(lim)=my(v=List([2])); forprime(p=2, lim, if((v[#v]+p)%5, , listput(v, p))); Vec(v) \\ Charles R Greathouse IV, Apr 13 2015

Crossrefs

Cf. A175451.

Sequence in context: A106306 A069104 A003631 * A032449 A278697 A129941

Adjacent sequences: A175440 A175441 A175442 * A175444 A175445 A175446

Keyword

nonn,easy

Author

Zak Seidov, May 28 2010

Status

approved