19105

Appears in sequences

• Composite n such that phi(n) * sigma(n) is one less than a square.at n=41A015709
• Odd composite n such that phi(n) * sigma(n) is one less than a square.at n=17A015722
• Number of distinct lines through the origin in 4-dimensional cube of side length n.at n=11A090026
• Minimal exponents m such that the fractional part of (101/100)^m obtains a maximum (when starting with m=1).at n=76A153671
• Numbers k such that the fractional part of (101/100)^k is greater than 1-(1/k).at n=7A153672
• Triangle T(n, k, m) = (m*(n-k) + 1)*T(n-1, k-1, m) + (m*k + 1)*T(n-1, k, m) + m*f(n,k)*T(n-2, k-1, m) with T(n, 0, m) = T(n, n, m) = 1, f(n, k) = 2*k if k <= floor(n/2) otherwise 2*(n-k), and m = 3, read by rows.at n=29A157278
• Triangle T(n, k, m) = (m*(n-k) + 1)*T(n-1, k-1, m) + (m*k + 1)*T(n-1, k, m) + m*f(n,k)*T(n-2, k-1, m) with T(n, 0, m) = T(n, n, m) = 1, f(n, k) = 2*k if k <= floor(n/2) otherwise 2*(n-k), and m = 3, read by rows.at n=34A157278
• Number of (n+2)X(5+2) 0..1 arrays x(i,j) with every row sum{j*x(i,j), j=1..5+2} equal, and every column sum{i*x(i,j), i=1..n+2} equal, with upper left element zero.at n=10A232651
• Interpret the values of the Moebius function mu(k) for k = n to 1 as a balanced ternary number.at n=9A292779
• a(n) is the least integer k such that k/Fibonacci(n) > 2/3.at n=23A293546
• a(n) is the integer k that minimizes |k/Fibonacci(n) - 2/3|.at n=23A293547
• Composite numbers k such that phi(k) * psi(k) + 1 is a perfect square, where phi is the Euler totient function (A000010) and psi is the Dedekind psi function (A001615).at n=33A309653
• a(n) is the smallest number that belongs simultaneously to the two arithmetic progressions prime(n) + m*prime(n+1) and prime(n+1) + m*prime(n+2), m >= 1, n >= 1.at n=42A319524