20625

Appears in sequences

• Odd numbers k that divide phi(k)*sigma(k).at n=18A015706
• A convolution triangle of numbers generalizing Pascal's triangle A007318.at n=32A049326
• Number of integers k such that phi(k) = 10^n.at n=24A072074
• Numbers k such that S(k)=d(k), where S(k) is the Kempner function (A002034) and d(k) is the number of divisors of k (A000005).at n=18A073307
• Numbers n such that number of divisors of n divides S(n), the Kempner function A002034.at n=29A073413
• Numbers k such that 4*k-1, 8*k-1, 16*k-1 and 32*k-1 are all primes.at n=12A101794
• a(n) = binomial(n+8, 8)*5^n.at n=3A140346
• a(n) = binomial(n+2,3)*5^3.at n=8A141480
• Number of n-digit numbers with each digit odd where the digits 1 and 3 occur an even number of times.at n=6A146086
• Number of (n+4)X8 binary arrays with every 1 having exactly three king-move neighbors equal to 1 but with no 2X2 blocks of 1s.at n=6A183461
• Number of (n+4)X11 binary arrays with every 1 having exactly three king-move neighbors equal to 1 but with no 2X2 blocks of 1s.at n=3A183464
• T(n,k)=Number of (n+4)X(k+4) binary arrays with every 1 having exactly three king-move neighbors equal to 1 but with no 2X2 blocks of 1s.at n=48A183465
• T(n,k)=Number of (n+4)X(k+4) binary arrays with every 1 having exactly three king-move neighbors equal to 1 but with no 2X2 blocks of 1s.at n=51A183465
• Number of 2 X 2 matrices having all terms in {1,...,n} and determinant = 0 (mod 3).at n=14A210698
• Number of 2 X 2 matrices having all elements in {0,1,...,n} and determinant = 0 (mod 3).at n=14A211033
• Numbers divisible by prime(d) for each digit d in their base-6 representation, none of which may be zero.at n=35A256876
• Primitive values n such that the square with opposite corners (0,0) and (n,n) contains a point (x,y) with integer coordinates, with 0 < x,y < n, at an integer distance from three of the four corners.at n=28A260549
• Number of length-4 0..n arrays with no repeated value differing from the previous repeated value by other than plus two, zero or minus 1.at n=10A269620
• Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 641", based on the 5-celled von Neumann neighborhood.at n=24A273311
• Number of permutations of n elements divided by the number of quaternary heaps on n+1 elements.at n=26A273732