21717

Appears in sequences

• Numbers k that divide s(k), where s(1)=1, s(j)=19*s(j-1)+j.at n=26A014869
• a(n) = a(1) + a(2) + ... + a(n-1) - a(m) for n >= 3, where m = 2^(p+1) + 2 - n and p is the unique number such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = 1 and a(2) = 2.at n=16A049905
• Numbers k such that 10^k + 7 is prime.at n=19A088274
• Number of (n+1)X(1+1) 0..2 arrays with every element both >= and <= some horizontal or vertical neighbor.at n=4A232117
• Number of (n+1)X(5+1) 0..2 arrays with every element both >= and <= some horizontal or vertical neighbor.at n=0A232121
• T(n,k) = Number of (n+1) X (k+1) 0..2 arrays with every element both >= and <= some horizontal or vertical neighbor.at n=10A232124
• T(n,k) = Number of (n+1) X (k+1) 0..2 arrays with every element both >= and <= some horizontal or vertical neighbor.at n=14A232124
• T(n,k)=Number of (n+1)X(k+1) 0..2 arrays with every element both >= and <= some horizontal, diagonal or antidiagonal neighbor.at n=14A232414
• Number of (5+1)X(n+1) 0..2 arrays with every element both >= and <= some horizontal, diagonal or antidiagonal neighbor.at n=0A232419
• Intersection of A003052 and A283002.at n=35A283003
• Numbers m > 0 that have a divisor d > 1 with binomial(m+d, d) == 1 mod m.at n=36A290040
• Numbers of the form HMMSS with primes H < 24 and MM, SS < 60, for which the number of seconds after midnight, 3600*H+60*MM+SS, is also prime.at n=35A295011
• Number of n X 5 0..1 arrays with each 1 horizontally or vertically adjacent to 2 or 4 1's.at n=7A295202
• Sequences n*(n+1)*(6*n+1)/2 and n*(n+1)*(7*n+1)/2 interleaved.at n=36A296636
• Numbers that are the sum of eight fourth powers in exactly eight ways.at n=35A345840
• Numbers k such that the k-th triangular number is a binary palindrome.at n=39A350988