A232558 a(1)=5, q=a(n) is the smallest prime > a(n-1) such that q-2*n = p prime

5, 7, 11, 13, 17, 19, 31, 47, 59, 61, 83, 97, 109, 131, 137, 139, 173, 193, 211, 233, 239, 241, 257, 271, 277, 281, 283, 307, 389, 397, 409, 431, 433, 457, 467, 491, 523, 563, 569, 571, 653, 661, 673, 701, 709, 733, 821, 823, 859, 887, 911, 967, 983, 991

Offset

1,1

Comments

Conjecture: the sequence is infinite.

Remarks: the primes p appears in increasing order but with repetition, all the primes are not present in p,q.

Links

Pierre CAMI, Table of n, a(n) for n = 1..10000

Example

5-3=2 a(1)=5
7-3=4 a(2)=7
11-5=6 a(3)=11
13-5=8 a(4)=13
17-7=10 a(5)=17

Mathematica

a[1]=5; a[n_]:=a[n]=(For[k=a[n-1]+2, !(k>2n&&PrimeQ[k]&&PrimeQ[k-2n]), k++]; k)

Crossrefs

Cf. A020483

Sequence in context: A191056 A314296 A141639 * A290246 A024891 A277907

Adjacent sequences: A232555 A232556 A232557 * A232559 A232560 A232561

Keyword

nonn

Author

Pierre CAMI, Nov 26 2013

Status

approved