A373799 Index of n-th prime in A374965.

2, 5, 9, 14, 19, 22, 25, 36, 38, 43, 47, 51, 56, 65, 72, 74, 76, 97, 100, 102, 105, 107, 110, 112, 115, 122, 125, 128, 130, 238, 255, 260, 272, 284, 286, 290, 293, 296, 300, 316, 325, 331, 562, 565, 567, 575, 578, 607, 610, 612, 617, 627, 632, 649, 651, 654, 866, 875, 878

Offset: 1

Author

Harvey P. Dale and N. J. A. Sloane, Jul 28 2024

Keywords

• nonn

Examples

			The fifth prime in order of appearance in A374965 is A375028(5) = 751 = A374965(19), so a(5) = 19.
		

Links

• N. J. A. Sloane, Table of n, a(n) for n = 1..290 (Terms 1 through 289 were obtained using _Harvey P. Dale_'s MMA program for A373798. For a(290), see A375028.)
• N. J. A. Sloane, A Nasty Surprise in a Sequence and Other OEIS Stories, Experimental Mathematics Seminar, Rutgers University, Oct 10 2024, Youtube video; Slides [Mentions this sequence]

Crossrefs

Cf. A373798 (first differences), A374965, A375028.

Programs

Python

from itertools import count, islice
from sympy import isprime, nextprime
def A373799_gen(): # generator of terms
    a, p = 1, 3
    for i in count(1):
        if isprime(a):
            yield i
            a = p-1
        else:
            a = (a<<1)+1
        p = nextprime(p)
A373799_list = list(islice(A373799_gen(),20)) # Chai Wah Wu, Jul 29 2024