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A105440 Highly cototient numbers that are prime, or intersection of A000040 and A100827. 1
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 (list; graph; refs; listen; history; text; internal format)
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

Table of n, a(n) for n=1..42.

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: A068835 A156557 A002428 * 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

STATUS

approved

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Last modified December 13 23:26 EST 2018. Contains 318087 sequences. (Running on oeis4.)