49995000

Appears in sequences

• a(n) = 10^n*(10^n-1)/2.at n=4A037182
• Images of hexamorphic numbers: suppose k-th hexagonal number H(k) (A000384) ends in k; sequence gives positive values of H(k).at n=16A038494
• Kaprekar numbers: numbers k such that k = q + r and k^2 = q*10^m + r, for some m >= 1, q >= 0 and 0 <= r < 10^m. Here q and r must both have the same number of digits.at n=41A045913
• Numbers n such that n and its 10's complement are both triangular numbers; that is, n and 10^k - n (where k is the number of digits in n) are triangular numbers.at n=19A068812
• Triangular numbers obtained as the concatenation of n and n+1.at n=13A226788
• Kaprekar numbers that are the concatenation of two consecutive numbers.at n=9A381918
• Kaprekar numbers (A006886) that are divisible by the sum of their digits.at n=29A382165