A046036 Indices of the concatenation of the first k odd numbers (A019519) which are primes.

2, 10, 16, 34, 49, 2570

Offset: 1

Author

Eric W. Weisstein

Keywords

• nonn
• base
• more
• changed

Comments

No others with k <= 12000. - Eric W. Weisstein, Mar 01 2004

No others with k <= 25000. - Michael S. Branicky, Aug 28 2025

Links

• H. Ibstedt, A Few Smarandache Integer Sequences, Smarandache Notions Journal, Vol. 8, No. 1-2-3, 1997, pp. 171-183.
• Eric Weisstein's World of Mathematics, Consecutive Number Sequences
• Eric Weisstein's World of Mathematics, Integer Sequence Primes
• Index entries for sequences related to Most Wanted Primes video

Crossrefs

Cf. A019519, A048847, A066811.

Programs

Mathematica

Module[{nn=50,odds},odds=Range[1,2nn+1,2];Position[Table[ FromDigits[ Flatten[IntegerDigits/@Take[odds,n]]],{n,nn}],?(PrimeQ[#]&)]]// Flatten (* The program generates the first 5 terms of the sequence. To generate the 6th, increase the value of nn to 2570 or more, but the program will take a long time to run. *) (* _Harvey P. Dale, Jul 21 2021 *)

Formula

a(n) = (A066811(n)+1)/2. - Michel Marcus, Jan 31 2014