The OEIS mourns the passing of Jim Simons and is grateful to the Simons Foundation for its support of research in many branches of science, including the OEIS.
The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A155548 Primes p such that p and the p-th prime have the same number of prime digits. 3
 2, 3, 7, 17, 37, 47, 73, 83, 89, 97, 113, 163, 179, 193, 197, 251, 347, 359, 383, 397, 421, 431, 443, 487, 541, 547, 571, 593, 607, 617, 631, 653, 673, 677, 719, 727, 743, 751, 761, 787, 821, 829, 857, 877, 881, 883, 947, 971, 1009, 1013, 1019, 1021, 1051, 1087 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Prime digit = 2, 3, 5 or 7. LINKS Table of n, a(n) for n=1..54. EXAMPLE 2 is a term because 2 is prime, prime(2)=3, and 2 and 3 each have 1 prime digit. 3 is a term because 3 is prime, prime(3)=5, and 3 and 5 each have 1 prime digit. 4 is not a term because 4 is not prime. 5 is prime, but prime(5)=11, and 5 has 1 prime digit while 11 has 0 prime digits, so 5 is not a term. MAPLE mm := proc (m) options operator, arrow: convert(m, base, 10) end proc: a := proc (n) local t, s, j: t := 0: s := 0: for j to nops(mm(n)) do if isprime(mm(n)[j]) = true then t := t+1 else end if end do: for j to nops(mm(ithprime(n))) do if isprime(mm(ithprime(n))[j]) = true then s := s+1 else end if end do: if isprime(n) = true and t = s then n else end if end proc: seq(a(n), n = 1 .. 1300); # Emeric Deutsch, Jan 28 2009 CROSSREFS Cf. A000040, A109066. Sequence in context: A077007 A158498 A267601 * A191033 A105554 A145230 Adjacent sequences: A155545 A155546 A155547 * A155549 A155550 A155551 KEYWORD nonn,base AUTHOR Juri-Stepan Gerasimov, Jan 24 2009 EXTENSIONS Corrected (added 761, 857; deleted 977) and extended by Emeric Deutsch, Jan 28 2009 Edited by Jon E. Schoenfield, Jan 20 2019 STATUS approved

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

Last modified May 26 08:09 EDT 2024. Contains 372807 sequences. (Running on oeis4.)