A105440 Highly cototient numbers that are prime, or intersection of A000040 and A100827.

2, 23, 47, 59, 83, 89, 113, 167, 269, 389, 419, 509, 659, 839, 1049, 1259, 1889, 2099, 2309, 2729, 3359, 3989, 4289, 4409, 5879, 6089, 6719, 9029, 9239, 10289, 10709, 11549, 13649, 13859, 15329, 15959, 20789, 21839, 23099, 25409, 27299, 30029, 34649, 43889, 51869

Offset

1,1

Comments

2 is definitely a "highly cototient prime". Oddly enough, though, PrimeFan does not list it as safe prime that is also a highly cototient number in RNTFS00013 even though he considers 1 to be a prime. - Robert Happelberg (roberthappelberg(AT)yahoo.com), Oct 04 2005

115 of the first 229 terms (just over 50%) of A100827 are prime. - Jud McCranie, May 18 2017

Links

Amiram Eldar, Table of n, a(n) for n = 1..115

PrimeFan, Listing of Esoteric Integer Sequences, See RNTFS00013, RNTFS00014.

Example

269 (after 59 & 89) is the first prime in a sequence of primes which are congruent to 9 mod 10.

Crossrefs

Cf. A000040, A100827.

Sequence in context: A156557 A002428 A325145 * A139831 A049592 A054679

Adjacent sequences: A105437 A105438 A105439 * A105441 A105442 A105443

Keyword

nonn

Author

Paul Muljadi, Sep 22 2005

Extensions

More terms from Robert Happelberg (roberthappelberg(AT)yahoo.com), Oct 04 2005

More terms from T. D. Noe, Mar 16 2010

More terms from Amiram Eldar, Dec 24 2020

Status

approved