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.

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A234647 Primes of the form q(p) - 1, where p is a prime and q(.) is the strict partition function (A000009).

Original entry on oeis.org

2, 11, 17, 37, 53, 103, 1259, 1609, 5119, 9791, 70487, 570077, 20792119, 281138047, 23515017983, 35692320959, 48626519093, 3626048321047, 27077619952639, 1651411233432319, 10743948315198451, 13378670620050079, 39413984631175423, 58553713102334907283, 145464242180631569963, 25408177717067357968543, 1374387931601409538722802926765483199, 20557774525717988142856527912112710143, 326033386646595458662191828888146112979, 27403889354101748193301659902924397784656229
Offset: 1

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Author

Zhi-Wei Sun, Dec 29 2013

Keywords

Comments

Though the primes in this sequence are very rare, by the conjecture in A234615 there should be infinitely many such primes.
See A234644 for a list of known primes p with q(p) - 1 prime.

Crossrefs

Programs

  • Maple
    a(1) = 2 since 2 = q(5) - 1 with 2 and 5 both prime.
  • Mathematica
    p[n_]:=A234615(n)
    Table[PartitionsQ[p[n]]-1,{n,1,30}]

Formula

a(n) = A000009(A234615(n)) - 1.

A236418 Primes p with A047967(p) also prime.

Original entry on oeis.org

13, 23, 43, 53, 71, 83, 107, 257, 269, 313, 1093, 2659, 2851, 3527, 8243, 20173, 20717, 24329, 26161, 26237, 31583, 53611, 60719, 74717, 83401, 118259, 118369, 130817, 133811, 145109, 152381, 169111, 178613, 183397, 205963
Offset: 1

Views

Author

Zhi-Wei Sun, Jan 25 2014

Keywords

Comments

According to the conjecture in A236417, this sequence should have infinitely many terms.

Examples

			a(1) = 13 with 13 and A047967(13) = 83 both prime.
		

Crossrefs

Programs

  • Mathematica
    pq[n_]:=PrimeQ[n]&&PrimeQ[PartitionsP[n]-PartitionsQ[n]]
    n=0;Do[If[pq[m],n=n+1;Print[n," ",m]],{m,1,10000}]
    Select[Prime[Range[20000]],PrimeQ[PartitionsP[#]-PartitionsQ[#]]&] (* Harvey P. Dale, Jan 02 2022 *)

A234900 Primes p with P(p+1) also prime, where P(.) is the partition function (A000041).

Original entry on oeis.org

2, 3, 5, 131, 167, 211, 439, 2731, 3167, 3541, 4261, 7457, 8447, 18289, 22669, 23201, 23557, 35401, 44507, 76781, 88721, 108131, 126097, 127079, 136319, 141359, 144139, 159169, 164089, 177487, 202627, 261757, 271181, 282911, 291971, 307067, 320561, 389219, 481589, 482627, 602867, 624259, 662107, 682361, 818887, 907657, 914189, 964267, 1040191, 1061689
Offset: 1

Views

Author

Zhi-Wei Sun, Jan 01 2014

Keywords

Comments

It seems that this sequence contains infinitely many terms.
See also A234569 for a similar sequence.

Examples

			a(1) = 2 since P(2+1) = 3 is prime.
a(2) = 3 since P(3+1) = 5 is prime.
a(3) = 5 since P(5+1) = 11 is prime.
		

Crossrefs

Programs

  • Mathematica
    p[k_]:=p[k]=PrimeQ[PartitionsP[Prime[k]+1]]
    n=0;Do[If[p[k],n=n+1;Print[n," ",Prime[k]]],{k,1,10000}]
Previous Showing 11-13 of 13 results.