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A195993 Numbers n such that 90n + 73 is prime. 21
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

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

FORMULA

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

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 *)

PROG

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

CROSSREFS

Cf. A181732, A198382.

Sequence in context: A162016 A242040 A206822 * A010456 A072496 A306482

Adjacent sequences:  A195990 A195991 A195992 * A195994 A195995 A195996

KEYWORD

nonn,easy

AUTHOR

J. W. Helkenberg, Oct 27 2011

STATUS

approved

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Last modified August 24 18:12 EDT 2019. Contains 326295 sequences. (Running on oeis4.)