login
A178180
Numbers k such that prime(2k) mod prime(k) = prime(2k+2) mod prime(k+1).
1
1, 8, 18, 21, 39, 40, 51, 55, 67, 85, 86, 87, 123, 175, 179, 185, 199, 200, 216, 227, 247, 248, 260, 292, 314, 351, 360, 361, 407, 413, 434, 441, 445, 465, 479, 494, 514, 515, 565, 573, 576, 580, 583, 622, 629, 670, 679, 684, 691, 698, 712, 717, 724, 734
OFFSET
1,2
FORMULA
prime(2*a(n)) mod prime(a(n)) = prime(2*a(n)+2) mod prime(a(n)+1).
EXAMPLE
a(2)=8 because prime(2*8) mod prime(8) = prime(2*8+2) mod prime(8+1) = 15.
MAPLE
A178180:=n->`if`((ithprime(2*n) mod ithprime(n)) = (ithprime(2*n+2) mod ithprime(n+1)), n, NULL): seq(A178180(n), n=1..10^3); # Wesley Ivan Hurt, Sep 14 2014
MATHEMATICA
Select[Range[800], Mod[Prime[2#], Prime[#]]==Mod[Prime[2#+2], Prime[#+1]]&] (* Harvey P. Dale, May 28 2019 *)
PROG
(PARI) s=[]; for(n=1, 1000, if(prime(2*n)%prime(n) == prime(2*n+2)%prime(n+1), s=concat(s, n))); s \\ Colin Barker, Jun 27 2014
CROSSREFS
Cf. A000040.
Sequence in context: A277557 A108060 A279688 * A269311 A242185 A273527
KEYWORD
nonn
AUTHOR
EXTENSIONS
Corrected by R. J. Mathar, Dec 22 2010
More terms from Colin Barker, Jun 27 2014
STATUS
approved