67066

Appears in sequences

• Expansion of (1+x)(1+x^2)/(1-x-x^3).at n=28A003410
• Expansion of (1 - x^2)/(1 - x - x^3).at n=32A058278
• Expansion of (1-x)/(1-x-2*x^2-x^3).at n=16A078007
• Least number 2k such that p^2 divides the numerator of the Bernoulli number B(2k), where p is the n-th irregular prime, A000928(n).at n=18A092681
• a(n) = Sum_{k=0..n} C(n-k, floor(k/2)).at n=29A097333
• Positions of the positive integers in the ordering of rational numbers as generated by the rules: 1 is in S, and if nonzero x is in S, then x+1 and -1/x are in S. (See Comments.)at n=27A226136
• Positions of the integers in the ordering of rational numbers as generated by the rules: 1 is in S, and if nonzero x is in S, then x+1 and -1/x are in S. (See Comments.)at n=37A226137
• Number of new rationals produced at the n-th iteration by applying the map t -> {t+1, -1/t} to nonzero terms, starting with S[0] = {1}.at n=29A226275
• Semiprime numbers that are sandwiched between products of exactly 4 distinct primes (or tetraprimes).at n=3A375964