18668

Appears in sequences

• Number of subsets of { 1, ..., n } containing an A.P. of length 7.at n=18A018792
• Revert transform of ((x - 1)(x + 1))/(-1 - x + x^3).at n=11A049130
• Numbers n such that 6*10^n-1 is prime.at n=23A056716
• Position of 5^n in A051037 (5-smooth numbers).at n=31A188427
• Potential magic constants of 8 X 8 magic squares composed of consecutive primes.at n=37A189188
• Partial sums of the second power of arithmetic derivative function A003415.at n=35A231864