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A295405 a(n) = 1 if n^2+1 is prime, 0 otherwise. 3
1, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1 (list; graph; refs; listen; history; text; internal format)
OFFSET
1
COMMENTS
It is conjectured that n^2+1 is prime infinitely often.
LINKS
Antti Karttunen, Table of n, a(n) for n = 1..100000 (first 10000 terms from Simon Plouffe)
FORMULA
a(n) = A010051(A002522(n)). - Robert Israel, Nov 22 2017
EXAMPLE
With n=1, a(1) = 2, n=2, a(2) = 5, a(3) = 0 since 10 is not prime.
MAPLE
seq(`if`(isprime(n^2+1), 1, 0), n=1..100); # Robert Israel, Nov 22 2017
MATHEMATICA
Boole[PrimeQ[Range[150]^2+1]] (* Paolo Xausa, Feb 23 2024 *)
PROG
(PARI) a(n)=isprime(n^2+1)
CROSSREFS
Characteristic function of A005574.
Cf. also A355449.
Sequence in context: A323509 A197183 A357382 * A267001 A141735 A343999
KEYWORD
nonn
AUTHOR
Simon Plouffe, Nov 22 2017
EXTENSIONS
Data section extended up to term a(120) by Antti Karttunen, Jul 12 2022
STATUS
approved

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Last modified March 29 05:16 EDT 2024. Contains 371264 sequences. (Running on oeis4.)