A075521 -id:A075521 - cp's OEIS frontend

A075519 Primes p such that floor(p/4) is prime.

11, 13, 23, 29, 31, 47, 53, 71, 79, 127, 149, 151, 167, 173, 191, 239, 269, 271, 293, 317, 359, 389, 431, 439, 509, 557, 599, 607, 631, 653, 719, 727, 773, 797, 911, 919, 967, 1031, 1087, 1109

Offset: 1

Reinhard Zumkeller, Sep 19 2002

nonn

			23 is a term, as 23 = 4*5 + 3.

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Cf. A075518, A075521.

[p: p in PrimesUpTo(2000)| IsPrime(Floor(p/4))]; // Vincenzo Librandi, Aug 04 2013

Select[Prime[Range[6! ]],PrimeQ[Floor[ #/4]]&] (* Vladimir Joseph Stephan Orlovsky, Nov 25 2009 *)

Definition corrected by Eric M. Schmidt, Aug 04 2013

A075522 Number of steps to reach the first nonprime (=A075523(n)) starting with the n-th prime p and iterating the map k -> 4*k+(p mod 4), or -1 if no integer is ever reached.

Original entry on oeis.org

1, 1, 1, 3, 3, 2, 1, 2, 1, 1, 2, 2, 1, 1, 2, 1, 2, 1, 3, 1, 2, 1, 1, 1, 2, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 4, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 1, 2, 2, 2, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 3, 1, 1, 1, 1, 1, 3, 1, 2, 1, 2, 1, 1, 1, 1, 1, 1, 1, 1, 1, 4

Offset: 1

Reinhard Zumkeller, Sep 19 2002

nonn

a(A075521(n)) > 1;

a(n) = a(A075520(n))+1 for n with A075520(n) prime.

			A000040(4)=7 and (7 mod 4) = 3: 7 -> 4*7+3=31 -> 4*31+3=127 -> 4*127+3=511 = A075523(4), therefore a(4)=3.

Cf. A075520, A075519.

cp's OEIS Frontend

A075519 Primes p such that floor(p/4) is prime.

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