A085725 -id:A085725 - cp's OEIS frontend

13, 19, 23, 43, 61, 67, 73, 83, 101, 139, 151, 173, 223, 251, 383, 457, 571, 673, 761

Offset: 1

Eric Chen, Dec 24 2014

The next candidate after 571 is 859. 859# + 1 is a 359-digit composite with no known factors. - Hugo Pfoertner, Feb 05 2021

			a(1) = 13 so 13# + 1 = 30031 = 59 * 509 is a semiprime.

factordb.com, Status of 859#+1.
Hisanori Mishima, Factorizations of many number sequences, PI Pn + 1 (n = 1 to 110) (2012).

Prime[#]&/@(Module[{pmrl=FoldList[Times,Prime[Range[50]]]},Position[ pmrl, ?(PrimeOmega[ #+1]==2&)]]//Flatten) (* _Harvey P. Dale, Apr 29 2017 *)

a(n) = prime(A085725(n)). - Hugo Pfoertner, Feb 05 2021

a(16)-a(18) using factordb.com from Hugo Pfoertner, Feb 05 2021

Missing 571 inserted by Sean A. Irvine, Mar 03 2023

4, 7, 10, 11, 14, 17, 20, 21, 25, 26, 48, 51, 55, 85, 96, 127, 149, 150, 170

Offset: 1

Sean A. Irvine, Oct 21 2023

isok(k) = bigomega(-1 + prod(j=1, k, prime(j))) == 2;

a(n) = primepi(A104876(n)).

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