A195993 Numbers n such that 90n + 73 is prime.

0, 1, 4, 5, 6, 9, 11, 12, 15, 18, 19, 20, 22, 23, 27, 28, 29, 32, 36, 39, 40, 42, 43, 49, 51, 54, 55, 56, 61, 62, 63, 65, 70, 72, 74, 75, 85, 88, 91, 92, 93, 95, 96, 97, 98, 103, 104, 106, 109, 110, 113, 114, 116, 127, 128, 131

Offset: 1

Author

J. W. Helkenberg, Oct 27 2011

Keywords

• nonn
• easy

Comments

This sequence results from the propagation (addition) of 12 Fibonacci-like sequences; this sequence contains (recovers) all digital root 1 and last digit 3 prime numbers.

Links

• Ivan Neretin, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A181732, A198382.

Programs

Maple

A142326 := proc(n)
        option remember;
        if n = 1 then
                73 ;
        else
                a := nextprime(procname(n-1)) ;
                while (a mod 45) <> 28 do
                        a := nextprime(a) ;
                end do;
                return a;
        end if;
end proc:
A195993 := proc(n)
        (A142326(n)-73)/90 ;
end proc:
seq(A195993(n),n=1..80) ; # R. J. Mathar, Oct 31 2011

Mathematica

Select[Range[0,200],PrimeQ[90#+73]&] (* Harvey P. Dale, May 05 2014 *)

PARI

is(n)=isprime(90*n+73) \\ Charles R Greathouse IV, Apr 25 2016

Formula

a(n) = (A142326(n)-73)/90.