21151

Appears in sequences

• Numerators of continued fraction convergents to sqrt(895).at n=4A042730
• Least number beginning with n such that every concatenation is a prime.at n=20A090506
• Semiprimes for which both the sum and the product of the digits is also a semiprime.at n=39A118690
• Numbers with digital product = 10.at n=33A199990
• Composite numbers whose product of digits is 10.at n=28A201057
• Number of n X 4 0..1 arrays avoiding 0 0 0 and 0 1 1 horizontally and 0 0 1 and 1 1 0 vertically.at n=11A207107
• Number of 4-length words w over n-ary alphabet such that 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=13A213283
• Odd composite numbers n, such that n, n+d, n*d and n/d are all odious (A000069) for every divisor d of n.at n=33A231558
• Numbers k such that 7*R_k + 10 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=14A256906
• Semiprimes such that sum of digits equals product of digits.at n=15A272436