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 A066902 Integers k such that phi(prime(k)+1) = phi(prime(k)-1). 2
 3, 5, 20, 156, 254, 377, 593, 1800, 5903, 5981, 7925, 18669, 19240, 41274, 48296, 135700, 146866, 228028, 234303, 251216, 407377, 654288, 802222, 886223, 938654, 1063412, 1072766, 1212140, 1238668, 1515063, 1609346, 2080991, 2097725, 2363130, 2408674, 2916514 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Integers k such that A008331(k) = A008330(k). LINKS Giovanni Resta, Table of n, a(n) for n = 1..675 FORMULA a(n) = primepi(A067890(n)). - Giovanni Resta, Apr 06 2020 MATHEMATICA Select[Range[1000000], EulerPhi[Prime[#]-1]==EulerPhi[Prime[#]+1]&] (* Harvey P. Dale, Feb 25 2012 *) PROG (PARI) isok(k) = my(p=prime(k)); eulerphi(p+1) == eulerphi(p-1); \\ Michel Marcus, Apr 06 2020 CROSSREFS Cf. A000010, A008864, A006093, A008330, A008331, A067890. Sequence in context: A197156 A171864 A256093 * A007363 A103991 A224994 Adjacent sequences: A066899 A066900 A066901 * A066903 A066904 A066905 KEYWORD nonn AUTHOR Benoit Cloitre, Jan 26 2002 EXTENSIONS More terms from Harvey P. Dale, Feb 25 2012 More terms from Jinyuan Wang, Apr 05 2020 STATUS approved

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Last modified June 21 20:04 EDT 2024. Contains 373559 sequences. (Running on oeis4.)