A373802 Primes in A373801 in order of their appearance.

2, 7, 29, 137, 7937, 569, 179, 809, 227, 263, 557, 40193, 797, 464897, 303868936193, 3833, 16097, 4457, 2309, 4793, 4937, 10289, 2693, 11057, 3002369, 52673, 27617, 1823, 7433, 1907, 497153, 4133, 269057, 2438716790407169, 2879, 2903, 93377, 2999

Offset

1,1

Comments

a(239) has 3137 decimal digits and is too long for inclusion in the b-file. - Alois P. Heinz, Aug 05 2024

Links

Alois P. Heinz, Table of n, a(n) for n = 1..238 (first 91 terms from N. J. A. Sloane)

Maple

b:= proc(n) option remember; (m->
     `if`(isprime(m), ithprime(n)+1, 2*m-1))(b(n-1))
    end: b(1):=2:
g:= proc(n) option remember; local k; for k from 1+g(n-1)
      while not isprime(b(k)) do od; k
    end: g(0):=0:
a:= n-> b(g(n)):
seq(a(n), n=1..38);  # Alois P. Heinz, Aug 05 2024

Mathematica

Reap[Module[{n = 1}, Nest[If[n++; PrimeQ[#], Sow[#]; Prime[n] + 1, 2*# - 1] &, 2, 500]]][[2, 1]] (* Paolo Xausa, Aug 07 2024 *)

Prog

(Python)
from itertools import count
from sympy import isprime, nextprime
def A373802_gen(): # generator of terms
    a, p = 2, 3
    for i in count(1):
        if isprime(a):
            yield a
            a = p+1
        else:
            a = (a<<1)-1
        p = nextprime(p)
A373802_list = list(islice(A373802_gen(), 20)) # Chai Wah Wu, Aug 05 2024

Crossrefs

Cf. A373801, A373803.

Sequence in context: A183608 A307389 A104252 * A018977 A190736 A265000

Adjacent sequences: A373799 A373800 A373801 * A373803 A373804 A373805

Keyword

nonn

Author

N. J. A. Sloane, Aug 05 2024

Status

approved