18729

Appears in sequences

• Base numbers of 9-gonal palindromic numbers.at n=17A055560
• Triangle read by rows: T(i,j) for the recurrence T(i,j) = (T(i-1,j) + 1)*i.at n=40A121662
• Number of binary arrays of length n+7 with no more than 4 ones in any length 8 subsequence (=50% duty cycle).at n=8A212398
• Number of length 2+2 0..n arrays with the sum of second differences squared multiplied by some arrangement of +-1 equal to zero.at n=25A250321
• Numbers k such that 25^k - 5^k - 1 is prime.at n=17A265483
• Numbers k that end with ( sum of digits of k )^2.at n=27A270343
• Triangle read by rows: T(m,n) = Sum_{i=1..n} P(m,i) where P(m,n) = m!/(m-n)! is the number of permutations of m items taken n at a time, for 1 <= n <= m.at n=40A285268
• The number of n-cell polyominoes with a line of symmetry parallel to the edges.at n=17A343562