A070156 Numbers k such that k-1, k+1, k^2+1 and k^4+1 are all prime numbers.
4, 6, 180, 3390, 18060, 19380, 34500, 92220, 92640, 96180, 114660, 127680, 133980, 140760, 159630, 161880, 172170, 207480, 254280, 255840, 263820, 296910, 309780, 378570, 380880, 397590, 408690, 422880, 432660, 440550, 511170, 540390, 572940
Offset: 1
Examples
For n = 6: 5, 7, 37, 1297 are all primes.
Links
- Amiram Eldar, Table of n, a(n) for n = 1..10000
Programs
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Mathematica
Do[s=n; If[PrimeQ[n-1]&&PrimeQ[n+1]&&PrimeQ[1+n^2] &&PrimeQ[1+n^4], Print[n]], {n, 1, 1000000}] -
PARI
is(k) = isprime(k-1) && isprime(k+1) && isprime(k^2+1) && isprime(k^4+1); \\ Amiram Eldar, Jun 21 2024
Extensions
Offset corrected by Amiram Eldar, Jun 21 2024