The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A120819 Indices of primes in A057137. 11
 171, 277, 367, 561, 567, 18881 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Digits are in ascending order beginning with 1 and after 9 comes 0. Indices of primes in A057137. All terms must end in 1 or 7: A057137(n) is even when n is even, and divisible by 3 iff n == 0, 2, 3, 5, 6, 8 or 9 (mod 10). - M. F. Hasler, Apr 14 2024 REFERENCES Clifford A. Pickover, A Passion for Mathematics, Wiley, 2005; see p. 61, 298. LINKS Table of n, a(n) for n=1..6. EXAMPLE a(1) = 12345678901234567890...01234567890...012345678901 = A057137(171) is the first prime term in A057137. MATHEMATICA fQ[n_] := PrimeQ@ FromDigits@ Mod[Range@n, 10]; lst = {}; Do[ If[fQ@n, AppendTo[lst, n]; Print@n], {n, 10000}]; lst IntegerLength[Select[Table[FromDigits[PadRight[{}, n, {1, 2, 3, 4, 5, 6, 7, 8, 9, 0}]], {n, 1, 1001, 2}], PrimeQ]] (* Harvey P. Dale, Feb 07 2024 *) PROG (PARI) N=0; for(n=1, 600, if(ispseudoprime(N=10*N+n%10), print1(n", "))) \\ Charles R Greathouse IV, May 10 2014 (Comment: Surprisingly, this is faster than calling ispseudoprime() only when n ends in 1 or 7, even when much larger N's are considered, e.g., up to 3000. - M. F. Hasler, Apr 14 2024) CROSSREFS Cf. A006055, A057137, A120828, A120820, A120821, A120822, A120823, A120824, A120825, A120826, A120827. Sequence in context: A136365 A031900 A349097 * A115078 A183996 A062907 Adjacent sequences: A120816 A120817 A120818 * A120820 A120821 A120822 KEYWORD base,hard,nonn,changed AUTHOR Robert G. Wilson v, Jul 05 2006 EXTENSIONS 18881 from Arjen K. Lenstra, Feb 20 2012 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified April 20 09:04 EDT 2024. Contains 371799 sequences. (Running on oeis4.)