cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-2 of 2 results.

A156152 Primes p such that p = 2 (mod pi(p)), where pi(p) = A000720(p) is the prime counting function.

Original entry on oeis.org

2, 5, 41, 47, 347, 367, 9559817, 514272793, 514274807, 514275529, 3779851091, 27788568469, 27788573621, 204475055227, 11091501631937, 81744303098923, 602656752070661, 602656752071189, 241849345578327359, 241849345578328451, 241849345578337811, 1784546064357416683
Offset: 1

Views

Author

M. F. Hasler, Feb 04 2009

Keywords

Crossrefs

Cf. A156151, A156153 (primes from this sequence).

Programs

  • Mathematica
    f[p_,n_]:=Mod[p,n]==2; lst={};Do[p=Prime[n];If[f[p,n],AppendTo[lst,p]],{n,11!}];lst (* Vladimir Joseph Stephan Orlovsky, Dec 08 2009 *)
  • PARI
    p=c=0; until(0, (-2+p=nextprime(p+1))%c++ || print1(p, ", "))

Formula

a(n) = A000040(A023144(n)).

Extensions

More terms from Max Alekseyev, May 03 2009
a(15)-a(16) from Jinyuan Wang, Feb 22 2020
Terms a(17) and beyond from Giovanni Resta, Feb 23 2020

A156150 Primes p such that p+2 = 0 (mod pi(p)) and pi(p)=A000720(p) is prime.

Original entry on oeis.org

31, 353, 9559783, 9559903
Offset: 1

Views

Author

M. F. Hasler, Feb 04 2009

Keywords

Comments

A subsequence of A156151.

Crossrefs

Cf. A156153.

Programs

  • PARI
    p=c=0; until(0, until( isprime(c++), p=nextprime(p+1)); (p+2)%c & next; print1( p","))

Formula

a(n) = A000040(A156149(n))
Showing 1-2 of 2 results.