

A093868


Smallest prime that differs from a multiple of n by unity.


4



2, 3, 2, 3, 11, 5, 13, 7, 17, 11, 23, 11, 53, 13, 29, 17, 67, 17, 37, 19, 41, 23, 47, 23, 101, 53, 53, 29, 59, 29, 61, 31, 67, 67, 71, 37, 73, 37, 79, 41, 83, 41, 173, 43, 89, 47, 281, 47, 97, 101, 101, 53, 107, 53, 109, 113, 113, 59, 353, 59, 367, 61, 127, 127, 131, 67, 269
(list;
graph;
refs;
listen;
history;
text;
internal format)



OFFSET

1,1


COMMENTS

Numbers n such that a(n1)=a(n+1)=n are A025584 (primes p such that p2 is not a prime).  Rick L. Shepherd, Aug 23 2004


LINKS

Robert Israel, Table of n, a(n) for n = 1..10000


FORMULA

a(n) = min(A034694(n), A038700(n)) for all n >= 1.  Rick L. Shepherd, Aug 23 2004


MAPLE

f:= proc(n) local j, k;
for k from 1 do
for j in [1, 1] do
if isprime(k*n+j) then return k*n+j fi
od od
end proc:
map(f, [$1..100]); # Robert Israel, Nov 07 2019


PROG

(PARI) a(n) = forprime(p=2, , if (!((p+1) % n)  !((p1) % n), return (p))); \\ Michel Marcus, Aug 08 2014


CROSSREFS

Cf. A093869.
Cf. A034694 (Smallest prime == 1 (mod n)), A038700 (Smallest prime == 1 (mod n)).
Sequence in context: A264766 A251090 A078331 * A194603 A183465 A223168
Adjacent sequences: A093865 A093866 A093867 * A093869 A093870 A093871


KEYWORD

nonn,look,changed


AUTHOR

Amarnath Murthy, Apr 20 2004


EXTENSIONS

More terms from Rick L. Shepherd, Aug 23 2004


STATUS

approved



