308880

Appears in sequences

• a(n) = n! * Catalan(n+1).at n=6A065866
• Triangle read by rows: see A128196 for definition.at n=40A126063
• a(n) = denominator of Sum_{k=1..n} k^mu(n+1-k), where mu(m) = A008683(m).at n=27A130492
• Number T(n,k) of length 2n k-ary words, either empty or beginning with the first letter of the alphabet and using each letter at least once, that can be built by repeatedly inserting doublets into the initially empty word; triangle T(n,k), n>=0, 0<=k<=n, read by rows.at n=35A256116
• a(n) is the denominator of Sum_{primes p < n} 1/(n-p).at n=28A305702
• Numbers that are product of a hexagonal number (A000384) and a square pyramidal numbers (A000330) in at least two ways.at n=33A306121
• Primitive 4-abundant numbers: Numbers k such that sigma(k) > 4k (A068404) all of whose proper divisors d are 4-deficient numbers (having sigma(d) < 4d).at n=24A307114
• Primitive terms of A023198: numbers k with the property sigma(k)/k >= 4 that are not divisible by any other number with that property.at n=26A392936