18391

Appears in sequences

• Number of palindromic semiprimes less than 10^n.at n=9A108505
• Numbers k such that k and k^2 use only the digits 1, 2, 3, 8 and 9.at n=14A136984
• Numerators of the difference between the squarefree totient analogs of the harmonic numbers and the harmonic numbers: F_n-H_n.at n=11A138320
• a(n) = 38*n^2 - 1.at n=21A158596
• Numerator of Laguerre(n, 6).at n=16A160631
• Positive integers of the form (7*m^2+1)/11.at n=30A179370
• Odd numbers m that are neither of the form p + 2^k nor of the form p - 2^k with 2^k < m, k >= 1, and p prime.at n=22A255967
• a(n) = A273059(4n+2).at n=23A275918
• Numbers k such that k!6 + 6 is prime, where k!6 is the sextuple factorial number (A085158 ).at n=23A287956
• a(n) = (9*2^n - 6*n - 10)/2.at n=11A308579
• Triangular array T(n,k), read by rows: coefficients of strong divisibility sequence of polynomials p(1,x) = 1, p(2,x) = 1 + 2*x, p(n,x) = u*p(n-1,x) + v*p(n-2,x) for n >= 3, where u = p(2,x), v = 1 + 3*x^2.at n=49A368518