A176024 Numbers k such that the reverse concatenation of the first k integers (A000422(k)) is a prime.

82, 37765

Offset

1,1

Comments

a(1) was pointed out by Artur Jasinski, Mar 30 2008 (see A000422).

a(2) was found by Eric W. Weisstein, Apr 06 2010.

a(3) > 84300. - Tyler Busby, Feb 21 2023

Links

Table of n, a(n) for n=1..2.

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

Example

a(1) is 82 since the 155-digit number 828180...54321 is prime.
a(2) is 37765 since the 177719-digit number 377653776437763...54321 is (a probable) prime.

Crossrefs

Cf. A000422, A007908, A176942.

Sequence in context: A241129 A289330 A282157 * A204976 A204703 A206648

Adjacent sequences: A176021 A176022 A176023 * A176025 A176026 A176027

Keyword

nonn,hard,more,base,bref

Author

Eric W. Weisstein, Apr 06 2010

Extensions

Edited by N. J. A. Sloane, Dec 03 2021

Status

approved