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 A222565 Primes that are the largest anti-divisor of primes. 5
 2, 3, 5, 7, 11, 13, 19, 29, 31, 41, 47, 53, 59, 67, 71, 73, 101, 109, 127, 131, 149, 151, 167, 179, 181, 211, 233, 239, 281, 293, 307, 311, 347, 349, 379, 401, 409, 421, 431, 439, 449, 461, 467, 479, 541, 547, 569, 571, 587, 607, 613, 619, 631, 647, 661, 673, 701 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS See A066272 for definition of anti-divisor. Primes p such that 2p + largest anti-divisor of 2p is also prime: 2, 5, 7, 11, 13, 29, 31, 41, 47, 59, 67, 79, 83, 101, 137, 139, 151, 157, 167, 173, 193, 223, 227, 239, 257,... LINKS Paolo P. Lava, Table of n, a(n) for n = 1..1000 FORMULA 2 together with primes of the form 4k+1 such that 6k+1 is prime, together with primes of the form 4k+3 such that 6k+5 is prime. - Charles R Greathouse IV, Feb 27 2013 EXAMPLE The prime 19 is here because it is largest anti-divisor of prime 29. MAPLE A222565 := proc(q) local a, b, k, n; for n from 2 to q do a:={}; b:=ithprime(n);   for k from 2 to b-1 do if abs((b mod k)-k/2)<1 then a:=a union {k}; fi; od;   k:=nops(a); b:=sort([op(a)]); if isprime(b[k]) then print(b[k]); fi; od; end: A222565(1000000); # Paolo P. Lava, Mar 08 2013 PROG (PARI) is(n)=isprime(n)&&isprime(bitor((3*n-1)\2, 1)) \\ Charles R Greathouse IV, Feb 27 2013 CROSSREFS Cf. A066481. Sequence in context: A237827 A114111 A155108 * A113188 A242738 A079153 Adjacent sequences:  A222562 A222563 A222564 * A222566 A222567 A222568 KEYWORD nonn AUTHOR Juri-Stepan Gerasimov, Feb 25 2013 EXTENSIONS Missing terms a(9), a(21), a(28), a(29) added by Charles R Greathouse IV, Feb 27 2013 STATUS approved

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Last modified July 3 16:27 EDT 2022. Contains 355055 sequences. (Running on oeis4.)