18507

Appears in sequences

• Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 90.at n=39A031588
• Numbers k such that prime(k) + prime(k+1)*2 is a square.at n=28A064504
• Number of planar n X n X n binary triangular grids symmetric both under 120 degree rotation and reflection with no more than 3 ones in any 5 X 5 X 5 subtriangle.at n=18A153928
• Number of ways to place zero or more nonadjacent 1,1 2,1 3,0 3,1 3,2 4,3 polyhexes in any orientation on a planar nXnXn triangular grid.at n=8A155274
• Numbers k such that A206369(k) = A206369(k + 1).at n=20A206368
• Numbers n such that uphi(n) = uphi(n+1), where uphi(n) is the unitary totient function (A047994).at n=26A287055
• Numbers k such that iphi(k) = iphi(k+1), where iphi(k) is an infinitary analog to the Euler totient function (A091732).at n=22A326403
• Numbers k such that A384247(k) = A384247(k+1).at n=32A385743