This site is supported by donations to The OEIS Foundation.

 Annual Appeal: Please make a donation to keep the OEIS running. In 2018 we replaced the server with a faster one, added 20000 new sequences, and reached 7000 citations (often saying "discovered thanks to the OEIS"). Other ways to donate

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 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 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

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

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