438480

Appears in sequences

• If X_1,...,X_n is a partition of a 2n-set X into 2-blocks then a(n) is equal to the number of 4-subsets of X containing none of X_i, (i=1,...,n).at n=26A130810
• A partition product of Stirling_1 type [parameter k = 4] with biggest-part statistic (triangle read by rows).at n=40A157394
• Number T(n,k) of words w of length n such that each letter of the k-ary alphabet is used at least once and for every prefix z of w we have #(z,a_i) = 0 or #(z,a_i) >= #(z,a_j) for all j>i and #(z,a_i) counts the occurrences of the i-th letter in z; triangle T(n,k), n>=0, 0<=k<=n, read by rows.at n=62A257783
• 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=32A307114
• Number of words w of length n such that each letter of the septenary alphabet is used at least once and for every prefix z of w we have #(z,a_i) = 0 or #(z,a_i) >= #(z,a_j) for all j>i and #(z,a_i) counts the occurrences of the i-th letter in z.at n=3A321843
• Expansion of e.g.f. exp(x^2) / (1 - x * exp(x^2/2)).at n=8A375633
• 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=34A392936