21293

Appears in sequences

• Numbers n such that 175*2^n-1 is prime.at n=25A050839
• a(n) = floor(1/(n-1) * Sum_{k=1..n-1} a(k)^(n/k)), given a(0)=1, a(1)=2, a(2)=3.at n=16A079116
• a(n) = 14*n^2 - 1.at n=38A158485
• Numbers n such that phi(n) = sigma(n) - reversal(sigma(n)).at n=7A230012
• a(n) = 2^n mod n^3.at n=32A233442
• Expansion of b(3)*b(4)/(1 - 2*x + x^2 - x^3 + x^4), where b(k) = (1-x^k)/(1-x).at n=20A266353
• Number of partitions of n for which the number of odd parts is equal to the positive alternating sum of the parts.at n=48A277103
• Number of compositions of n if only the order of parts 1 and 2 matters.at n=20A289249
• Expansion of g.f. A(x) satisfying A(x)^2 = A(x*A(x)) / (1-x) with A(0) = 0.at n=13A367387