19398656

Appears in sequences

• Denominators in the Maclaurin series for arctan(1+x).at n=36A075554
• a(i) = the number of occurrences of 9's in the palindromic compositions of n=2*i-1 = the number of occurrences of 10's in the palindromic compositions of n=2*i.at n=19A079862
• a(n) = (2*n + 1) * 2^(n + 1).at n=18A118417
• a(n) = n-th integer from among those positive integers with an exponent of n in their prime-factorizations.at n=18A123904
• a(n) = n*2^floor((n+1)/2).at n=37A132314
• a(n) = (n/4)*2^(n/2)*((1+sqrt(2))^2 + (-1)^n*(1-sqrt(2))^2).at n=37A187272
• Numbers k such that 2^phi(k) == phi(k)^2 (mod k^2).at n=20A319314