20427

Appears in sequences

• Denominators of continued fraction convergents to sqrt(698).at n=10A042343
• Number of nonempty subsequences {s(k)} of 1..n such that the difference sequence is palindromic.at n=22A053599
• Numbers k such that sigma(phi(k)) - phi(sigma(k)) is nonzero and divisible by sigma(k), that is A065395(k)/A000203(k) is a nonzero integer.at n=20A092588
• a(n) = 5*2^n - 4*n - 5.at n=11A126284
• a(n) = 169*n^2 - 2*n.at n=10A158218
• a(n) = number of n-lettered words in the alphabet {1, 2, 3} with as many occurrences of the substring (consecutive subword) [1, 2] as of [2, 3].at n=10A211281
• Number of partitions p of n such that (maximal multiplicity of the parts of p) >= (maximal part of p).at n=46A240313
• Number of partitions of n such that the number of even parts is a part and the number of odd parts is not a part.at n=43A240577
• a(n) = (1/24)*(n + 3)*(3*n^3 + 5*n^2 - 6*n + 16).at n=18A290061
• a(n) = a(n-1) + a(n-2) + a([n/2]), where a(0) = 1, a(1) = 1, a(2) = 1.at n=20A298338
• a(n) = Sum_{k=1..n} sigma( (n/gcd(k,n))^2 ).at n=26A372227