211117

Appears in sequences

• Expansion of (1+x)(1+x^2)/(1-x-x^3).at n=31A003410
• Quasi-Carmichael numbers to base -3: squarefree composites n such that for every prime p that divides n, p+3 divides n+3.at n=19A029563
• Expansion of (1 - x^2)/(1 - x - x^3).at n=35A058278
• a(n) = Sum_{k=0..n} C(n-k, floor(k/2)).at n=32A097333
• a(0) = 1, a(1) = 2, a(2) = 5; for n >= 3, a(n) = a(n-1) + 2*a(n-2) + a(n-3).at n=16A101399
• a(n) = a(n-3) + 2*a(n-6) + a(n-9).at n=48A109533
• 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=30A226136
• 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=41A226137
• 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=32A226275
• Positive integers k such that k divides 17^k + 2.at n=5A333414