A201818 Numbers k such that 90*k + 49 is prime.

1, 2, 4, 5, 8, 9, 11, 12, 15, 16, 17, 18, 19, 22, 26, 29, 30, 33, 34, 38, 39, 41, 43, 45, 50, 51, 52, 54, 55, 57, 60, 67, 72, 73, 74, 78, 79, 85, 86, 87, 89, 92, 93, 95, 96, 97, 100, 103, 107, 108, 109, 110, 111, 115, 121, 123, 125, 131, 134, 136, 137, 141

Offset: 1

Author

J. W. Helkenberg, Dec 05 2011

Keywords

• nonn
• easy

Comments

This sequence was generated by adding 14 Fibonacci-like sequences. Looking at the format 90*k+49 modulo 9 and modulo 10 we see that all entries of A142314 have digital root 2 and last digit 9. (Reverting the process is an application of the Chinese remainder theorem.)

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..10000

Programs

Magma

[n: n in [0..200] | IsPrime(90*n+49)] // Vincenzo Librandi, Dec 11 2011

Mathematica

Select[Range[0, 200], PrimeQ[90 # + 49] &] (* T. D. Noe, Dec 06 2011 *)

PARI

is(n)=isprime(90*n+49) \\ Charles R Greathouse IV, Feb 17 2017