A089986 - OEIS

A089986

Numbers n such that 4n + 7 is prime.

-1, 0, 1, 3, 4, 6, 9, 10, 13, 15, 16, 18, 19, 24, 25, 30, 31, 33, 36, 39, 40, 43, 46, 48, 51, 54, 55, 58, 61, 64, 66, 69, 75, 76, 81, 85, 88, 90, 93, 94, 103, 106, 108, 109, 114, 115, 118, 120, 121, 123, 124, 129, 135, 139, 141, 145, 148, 150, 153, 156, 159, 160, 163, 169

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,4

REFERENCES

M. Cerasoli, F. Eugeni and M. Protasi, Elementi di Matematica Discreta, Bologna 1988.

Emanuele Munarini and Norma Zagaglia Salvi, Matematica Discreta,UTET, CittaStudiEdizioni, Milano 1997.

LINKS

Table of n, a(n) for n=1..64.

FORMULA

a(n) = A005099(n) - 2 = A095278(n) - 1.

MAPLE

A089986:=n->`if`(isprime(4*n+7), n, NULL): seq(A089986(n), n=-1..200); # Wesley Ivan Hurt, Sep 18 2014

MATHEMATICA

Select[Range[-1, 200], PrimeQ[4 # + 7] &] (* Wesley Ivan Hurt, Sep 18 2014 *)

PROG

(Magma) [ n: n in [-1..170] | IsPrime(4*n+7) ];

(PARI) is(n)=isprime(4*n+7) \\ Charles R Greathouse IV, Feb 20 2017

CROSSREFS

Cf. A005099 ((( Primes = -1 mod 4 ) + 1)/4), A005098 (4n+1 is prime), A095278 (4n+3 is prime), A111215 (4n+5 is prime).

Sequence in context: A361837 A191326 A191185 * A101448 A299231 A005122

Adjacent sequences: A089983 A089984 A089985 * A089987 A089988 A089989

KEYWORD

sign

AUTHOR

Giovanni Teofilatto, Jan 13 2004

EXTENSIONS

Edited and extended by Klaus Brockhaus, Dec 22 2008

STATUS

approved