21416

Appears in sequences

• Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 73.at n=29A031571
• Denominators of continued fraction convergents to sqrt(929).at n=8A042797
• Numbers n which are a proper multiple (>1) of A068505(n) (= n read in base m+1 where m = largest digit of n).at n=35A089584
• Number of compositions of n into pairwise relatively prime parts.at n=22A101268
• Binomial transform of the characteristic function of the prime numbers (A010051).at n=16A121497
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 1, -1), (-1, 1, 0), (0, 0, -1), (1, 0, 1)}.at n=9A149135
• Numbers k such that 2^k + 25 is prime.at n=29A157006
• Numbers n such that the digits of sigma(n) are exactly the same (albeit in different order) as the digits of phi(n), in base 10.at n=24A175795
• Number of (n+1)X2 0..3 arrays with every 2 X 2 subblock having the number of clockwise edge increases equal to the number of counterclockwise edge increases in its adjacent leftward and upward neighbors.at n=2A205635
• Number of (n+1)X4 0..3 arrays with every 2 X 2 subblock having the number of clockwise edge increases equal to the number of counterclockwise edge increases in its adjacent leftward and upward neighbors.at n=0A205637
• T(n,k) = Number of (n+1)X(k+1) 0..3 arrays with every 2 X 2 subblock having the number of clockwise edge increases equal to the number of counterclockwise edge increases in its adjacent leftward and upward neighbors.at n=3A205642
• T(n,k) = Number of (n+1)X(k+1) 0..3 arrays with every 2 X 2 subblock having the number of clockwise edge increases equal to the number of counterclockwise edge increases in its adjacent leftward and upward neighbors.at n=5A205642
• Numbers n such that prime(n) contains a substring of all the prime digits in order, i.e., "2357".at n=14A295708
• Number of integer compositions of n with the same length as the absolute value of their alternating sum.at n=21A357183
• Number of set partitions of {1..n} such that the mean of the means of the blocks is (n+1)/2.at n=10A361910