500500

Appears in sequences

• Kaprekar numbers: positive numbers n such that n = q+r and n^2 = q*10^m+r, for some m >= 1, q >= 0 and 0 <= r < 10^m, with n != 10^a, a >= 1.at n=37A006886
• Coordination sequence for A_4 lattice.at n=35A008383
• 2nd elementary symmetric function of the first n+1 positive integers congruent to 2 mod 3.at n=24A024391
• a(n) = 10^n*(10^n+1)/2.at n=3A037156
• 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=19A045913
• The full list of 6-Kaprekar numbers.at n=16A053397
• Another version of the Kaprekar numbers (A006886): n such that n = q+r and n^2 = q*10^m+r, for some m >= 1, q >= 0 and 0 <= r < 10^m, with n != 10^a, a >= 1 and n an m-digit number.at n=34A053816
• Erroneous version of A006887.at n=38A060809
• Triangular numbers that contain exactly 2 different digits.at n=26A062691
• 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=12A068812
• a(1) = 1; a(n) is the smallest triangular number > a(n-1) which differs from it at every digit.at n=41A068855
• Triangular numbers containing 2n digits obtained by duplicating the first n digits; i.e., triangular numbers in A020338.at n=7A068899
• a(n) = (n^6 + n^3)/2.at n=10A071232
• Smallest multiple of n using only digits 0 and 5.at n=27A078244
• Triangular numbers in which the sum of the external digits equals the sum of the internal digits.at n=34A088289
• a(n) = A069537(n)/2.at n=18A088404
• Triangular numbers composed of digits {0,1,5}.at n=10A119039
• Triangular numbers composed of digits {0,2,5}.at n=4A119051
• Triangular numbers composed of digits {0,3,5}.at n=5A119061
• Triangular numbers composed of digits {0,4,5}.at n=6A119071