499500
domain: N
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=36A006886
- a(n) = 10^n*(10^n-1)/2.at n=3A037182
- Images of hexamorphic numbers: suppose k-th hexagonal number H(k) (A000384) ends in k; sequence gives positive values of H(k).at n=11A038494
- 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=18A045913
- The full list of 6-Kaprekar numbers.at n=15A053397
- 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=33A053816
- Erroneous version of A006887.at n=37A060809
- 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=11A068812
- Triangular numbers which are 9-almost primes.at n=14A076583
- a(n) = A000217(n^3) - n^3.at n=10A085744
- "Kaprekar quadruples": digits of X^4 taken D at a time sum to X (where D is number of digits in X.)at n=26A171493
- Triangular numbers which are sums of 6 consecutive primes.at n=22A173423
- Triangular numbers that are the product of 4 distinct triangular numbers greater than 1.at n=3A226501
- Triangular numbers obtained as the concatenation of n and n+1.at n=7A226788
- Triangular numbers n such that each decimal digit of n is equal to the difference of at least two other digits of n.at n=30A255917
- Triangular numbers k such that phi(k) is a square number, where phi(k) is the Euler totient function (A000010).at n=21A287473
- Square roots of terms in A238237.at n=22A290449
- The first of three consecutive hexagonal numbers the sum of which is equal to the sum of three consecutive primes.at n=20A298272
- Numbers m such that the largest digit in the decimal expansion of 1/m is 2.at n=37A341383
- Triangular numbers such that the three numbers before it and the three numbers after it are squarefree.at n=25A374393