21488

Appears in sequences

• Denominators of continued fraction convergents to sqrt(719).at n=12A042385
• Total Wiener index of double-star trees with n nodes.at n=31A186235
• Number of permutations of length n containing exactly 2 occurrences of 123 and 2 occurrences of 132.at n=12A224288
• Indices of the start of 10 successive distinct digits in the decimal expansion of e (2.718281828...).at n=17A258166
• Numbers which are representable as a sum of seventeen but no fewer consecutive nonnegative integers.at n=30A270302
• Let s(k) denote the sum of the even proper divisors of k. The sequence lists the pairs of numbers (x, y) such that s(x) = y and s(y) = x.at n=10A279812
• List of ordered pairs (x, y) from A279812.at n=10A279950
• Number A(n,k) of sets of nonempty words with a total of n letters over k-ary alphabet; square array A(n,k), n>=0, k>=0, read by antidiagonals.at n=61A292804
• Number of sets of nonempty words with a total of n letters over quaternary alphabet.at n=6A292838