A352929 Indices of primes in A093714.

2, 3, 4, 6, 8, 10, 13, 15, 17, 24, 28, 32, 36, 38, 42, 52, 54, 58, 64, 66, 70, 72, 78, 85, 89, 97, 99, 101, 103, 107, 123, 125, 133, 135, 143, 145, 153, 159, 161, 169, 175, 177, 185, 187, 193, 195, 203, 219, 221, 225, 227, 235, 237, 245, 251, 259, 263, 267, 269, 277, 279, 289, 303, 305, 309, 311, 325, 333, 341, 345, 349, 353, 363, 369, 375, 379, 385, 393

Offset

1,1

Comments

Note this is different from "a(n) = index of prime(n) in A093714", which would start 3, 2, 4, 6, 8, ..., but would otherwise be the same.

Links

Michael De Vlieger, Table of n, a(n) for n = 1..10000

Mathematica

nn = 400; c[_] = False; c[1] = True; j = 1; u = 2; Reap[Do[k = u; While[Nand[! TrueQ@ c[k], CoprimeQ[j, k], k != j + 1], k++]; Set[{j, c[k]}, {k, True}]; If[PrimeQ@ k, Sow[i]]; If[k == u, While[TrueQ@ c[u], u++]], {i, 2, nn}]][[-1, -1]] (* Michael De Vlieger, May 03 2022 *)

Prog

(Python)
from math import gcd
from sympy import isprime
from itertools import count, islice
def agen(): # generator of terms
    an, aset, mink = 1, {1}, 2
    for n in count(1):
        if isprime(an): yield n
        k = mink
        while k in aset or gcd(an, k) != 1 or k-an == 1: k += 1
        an = k
        aset.add(an)
        while mink in aset: mink += 1
print(list(islice(agen(), 78))) # Michael S. Branicky, May 03 2022

Crossrefs

Cf. A093714.

Sequence in context: A029517 A177907 A083006 * A096061 A100919 A184109

Adjacent sequences: A352926 A352927 A352928 * A352930 A352931 A352932

Keyword

nonn

Author

N. J. A. Sloane, May 03 2022

Status

approved