A201819 - OEIS

%I #16 Sep 08 2022 08:46:01

%S 0,2,6,7,8,11,13,14,15,16,19,20,22,25,26,28,30,33,35,36,37,39,40,47,

%T 49,51,53,60,61,63,64,65,68,71,74,75,76,77,81,82,84,85,88,91,92,95,97,

%U 99,104,107,110,112,118,120,128,130,131,138,139,141,146,149

%N Numbers n such that 90*n + 31 is prime.

%C This sequence was generated by adding 14 Fibonacci-like sequences. Looking at the format 90n+31 modulo 9 and modulo 10 we see that all entries of A142328 have digital root 4 and last digit 1. (Reverting the process is an application of the Chinese remainder theorem.)

%H Vincenzo Librandi, <a href="/A201819/b201819.txt">Table of n, a(n) for n = 1..10000</a>

%t Select[Range[0, 200], PrimeQ[90 # + 31] &] (* _T. D. Noe_, Dec 06 2011 *)

%o (Magma) [n: n in [0..200] | IsPrime(90*n+31)] // _Vincenzo Librandi_, Dec 11 2011

%o (PARI) is(n)=isprime(90*n+31) \\ _Charles R Greathouse IV_, Feb 20 2017

%Y Cf. A181732, A198382, A195993, A196000, A196007, A201739, A201734, A201804, A201816, A201818.

%K nonn,easy

%O 1,2

%A _J. W. Helkenberg_, Dec 05 2011