20518

Appears in sequences

• Number of permutations which are the union of an increasing and a decreasing subsequence.at n=9A029759
• Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 98 ones.at n=18A031866
• Numbers k such that 145*2^k+1 is prime.at n=20A032422
• Numbers k such that the decimal digits of phi(k) are a permutation of those of k.at n=25A115921
• Number of length n+3 0..5 arrays with no four consecutive terms having the maximum of any two terms equal to the minimum of the remaining two terms.at n=2A250384
• T(n,k)=Number of length n+3 0..k arrays with no four consecutive terms having the maximum of any two terms equal to the minimum of the remaining two terms.at n=23A250387
• Number of length 3+3 0..n arrays with no four consecutive terms having the maximum of any two terms equal to the minimum of the remaining two terms.at n=4A250389
• Möbius transform of A324118, where A324118(n) = A000593(A156552(n)).at n=85A324542
• a(n) = A324542(2*prime(n)).at n=13A324552
• Expansion of Product_{k>=1} (1 + x^sigma(k)) / (1 - x^sigma(k)).at n=34A333045
• Consider the figure made up of a row of n adjacent congruent rectangles, with diagonals of all possible rectangles drawn; a(n) = number of interior vertices where exactly three lines cross.at n=33A336489
• a(0) = ... = a(3) = 1; a(n) = Sum_{k=1..n-4} a(k) * a(n-k-4).at n=30A346048
• a(n) = Sum_{k=0..n} Stirling2(n,k) * binomial(7*k,k) / (6*k + 1).at n=5A346768
• Number of integer partitions of n with integer reverse-alternating product.at n=50A347445