A110949 Integers n such that 4*10^n + 61 is prime.

1, 2, 7, 11, 191, 248, 1067, 2666, 5252, 13400, 22886, 23739, 29095

Offset

1,2

Comments

See Kamada link - primecount.txt for terms, primesize.txt for discovery details including probable or proved primes - search on "40061".

a(14) > 10^5. - Robert Price, Jan 22 2017

Links

Table of n, a(n) for n=1..13.

Makoto Kamada, List of near-repdigit-related prime numbers.

Index entries for primes involving repunits.

Example

n = 7 is in the sequence because 4*10^7 + 61 = 4*10000000 + 61 = 40000000 + 61 = 40000061, which is prime.

Prog

(PARI) isok(n) = isprime(4*10^n+61); \\ Michel Marcus, Jan 22 2017

Crossrefs

Cf. A049054, A088274, A088275, A095688, A107083, A108049, A108050, A108052, A108054.

Sequence in context: A069885 A069748 A064441 * A226703 A126343 A344951

Adjacent sequences: A110946 A110947 A110948 * A110950 A110951 A110952

Keyword

more,nonn

Author

Julien Peter Benney (jpbenney(AT)ftml.net), Oct 04 2005

Extensions

a(9)-a(11) from Ray Chandler, Dec 23 2010

Prepended a(1)=1 by Robert Price, Jan 22 2017

a(12)-a(13) from Robert Price, Jan 22 2017

Status

approved