51663

Appears in sequences

• One half of the number of permutations of [n] such that the differences have 5 runs with the same signs.at n=3A000506
• Triangle T(n,k) = P(n,k)/2, n >= 2, 1 <= k < n, of one-half of number of permutations of 1..n such that the differences have k runs with the same signs.at n=32A008970
• Numbers k such that the smoothly undulating palindromic number (79*10^k - 97)/99 is a prime.at n=5A062226