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 A296079 a(n) = 1 if 1+phi(n) is prime, 0 otherwise, where phi = A000010, Euler totient function. 6
 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 0, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 0, 0, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 0, 1, 1, 1, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Out of the first 65537 values, 26197 are 1's (indicating primes), and 39340 are 0's, indicating nonprimes. LINKS Antti Karttunen, Table of n, a(n) for n = 1..65537 FORMULA a(n) = A010051(A039649(n)) = A010051(1+A000010(n)). For all n, a(n) >= A010051(n) and a(2n) >= A010051(n). MATHEMATICA Table[If[PrimeQ[EulerPhi[n]+1], 1, 0], {n, 120}] (* Harvey P. Dale, Apr 23 2020 *) PROG (PARI) A296079(n) = isprime(1+eulerphi(n)); CROSSREFS Characteristic function of A039698. Cf. A039689 (positions of zeros). Cf. also A296077, A296078, A296080. Sequence in context: A014451 A106667 A133011 * A340363 A340372 A167850 Adjacent sequences:  A296076 A296077 A296078 * A296080 A296081 A296082 KEYWORD nonn AUTHOR Antti Karttunen, Dec 05 2017 STATUS approved

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Last modified June 20 14:58 EDT 2021. Contains 345165 sequences. (Running on oeis4.)