781249

Appears in sequences

• a(n) = 2*5^n-1.at n=8A081655
• Numbers of the form i*5^j-1 (i=1..4, j >= 0).at n=33A181287
• Smallest number m > 1 such that m^2 == 1 (mod 10^n).at n=6A181539
• Numbers n with k digits such that n^2 == 1 (mod 10^k).at n=31A181607
• Majority value maps: number of nX4 binary arrays indicating the locations of corresponding elements equal to at least half of their horizontal, diagonal and antidiagonal neighbors in a random 0..3 nX4 array.at n=4A220991
• T(n,k)=Majority value maps: number of nXk binary arrays indicating the locations of corresponding elements equal to at least half of their horizontal, diagonal and antidiagonal neighbors in a random 0..3 nXk array.at n=32A220993
• a(n) = (2*5^(2^n) - 1) mod 10^n: a sequence of trimorphic numbers ending in 9.at n=5A224473
• (2*5^(2^n) + (10^n)/2 - 1) mod 10^n: a sequence of trimorphic numbers ending (for n > 1) in 9.at n=6A224475
• Numbers n such that the product of proper divisors of n ends with n and n is not a multiplicatively perfect number (A007422).at n=33A278474