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 1-3 of 3 results.

A142799 Primes congruent to 59 mod 60.

Original entry on oeis.org

59, 179, 239, 359, 419, 479, 599, 659, 719, 839, 1019, 1259, 1319, 1439, 1499, 1559, 1619, 1979, 2039, 2099, 2339, 2399, 2459, 2579, 2699, 2819, 2879, 2939, 2999, 3119, 3299, 3359, 3539, 3659, 3719, 3779, 4019, 4079, 4139, 4259, 4679, 4799, 4919, 5039, 5099
Offset: 1

Views

Author

N. J. A. Sloane, Jul 11 2008

Keywords

Crossrefs

Supersequence of A230809. Cf. A000040.

Programs

Formula

a(n) ~ 16n log n. - Charles R Greathouse IV, Jul 02 2016

A215850 Primes p such that 2*p + 1 divides Lucas(p).

Original entry on oeis.org

5, 29, 89, 179, 239, 359, 419, 509, 659, 719, 809, 1019, 1049, 1229, 1289, 1409, 1439, 1499, 1559, 1889, 2039, 2069, 2129, 2339, 2399, 2459, 2549, 2699, 2819, 2939, 2969, 3299, 3329, 3359, 3389, 3449, 3539, 3779, 4019, 4349, 4409, 4919, 5039, 5279, 5399, 5639
Offset: 1

Views

Author

Arkadiusz Wesolowski, Aug 24 2012

Keywords

Comments

An equivalent definition of this sequence: 5 together with primes p such that p == -1 (mod 30) and 2*p + 1 is also prime.
Sequence without the initial 5 is the intersection of A005384 and A132236.
These numbers do not occur in A137715.
From Arkadiusz Wesolowski, Aug 25 2012: (Start)
The sequence contains numbers like 1409 which are in A053027.
a(n) is in A002515 if and only if a(n) is congruent to -1 mod 60. (End)

Examples

			29 is in the sequence since it is prime and 59 is a factor of Lucas(29) = 1149851.
		

Crossrefs

Supersequence of A230809. Cf. A000032, A132236.

Programs

  • Magma
    [5] cat [n: n in [29..5639 by 30] | IsPrime(n) and IsPrime(2*n+1)];
    
  • Mathematica
    Select[Prime@Range[740], Divisible[LucasL[#], 2*# + 1] &]
    Prepend[Select[Range[29, 5639, 30], PrimeQ[#] && PrimeQ[2*# + 1] &], 5]
  • PARI
    is_A215850(n)=isprime(n)&!real((Mod(2,2*n+1)+quadgen(5))*quadgen(5)^n) \\ - M. F. Hasler, Aug 25 2012

A239548 Primes p such that gcd(Lucas(p), Mersenne(p)) > 1.

Original entry on oeis.org

2, 179, 239, 359, 419, 487, 659, 719, 883, 1013, 1019, 1439, 1459, 1499, 1559, 1723, 1871, 1993, 2039, 2339, 2399, 2459, 2593, 2699, 2819, 2939, 3041, 3299, 3329, 3359, 3539, 3779, 4019, 4813, 4919, 4957, 5039, 5231, 5261, 5279, 5399, 5639, 6011, 6353, 6373
Offset: 1

Views

Author

Arkadiusz Wesolowski, Mar 21 2014

Keywords

Examples

			239 is in the sequence since it is prime and 479 is a prime factor of both Lucas(239) and Mersenne(239) = 2^239 - 1.
		

Crossrefs

Supersequence of A230809.

Programs

  • Magma
    [p: p in PrimesUpTo(6500) | Gcd(Lucas(p),2^p-1) gt 1];
    
  • PARI
    for(p=2, 6373, if(isprime(p)&&gcd(fibonacci(p-1)+fibonacci(p+1), 2^p-1)>1, print1(p, ", ")));
Showing 1-3 of 3 results.