A033561 Primes p such that 6!+p is also prime.
7, 13, 19, 23, 31, 37, 41, 53, 67, 89, 101, 103, 107, 109, 137, 139, 157, 163, 167, 191, 199, 227, 233, 251, 257, 263, 271, 277, 293, 311, 313, 331, 349, 367, 373, 383, 389, 397, 409, 431, 433, 443, 461, 467, 503, 509, 557, 563, 569, 571, 577, 587, 599, 601, 607
Offset: 1
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Vincenzo Librandi)
Crossrefs
Cf. A054984.
Programs
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Magma
[p: p in PrimesUpTo(800)|IsPrime(p+720)]; // Vincenzo Librandi, Apr 10 2013
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Mathematica
Select[Prime[Range[800]], PrimeQ[# + 720]&] (* Vincenzo Librandi, Apr 10 2013 *)
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PARI
isok(k) = isprime(k) && sigma(k + 720) == sigma(k) + 720; \\ Amiram Eldar, Mar 08 2025