50005000
domain: N
Appears in sequences
- Smallest triangular number containing exactly n 0's.at n=5A036517
- a(n) = 10^n*(10^n+1)/2.at n=4A037156
- 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=42A045913
- Triangular numbers that contain exactly 2 different digits.at n=33A062691
- 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=20A068812
- Triangular numbers containing 2n digits obtained by duplicating the first n digits; i.e., triangular numbers in A020338.at n=13A068899
- a(n) = (n^8 + n^4)/2.at n=10A071231
- Triangular numbers composed of digits {0,1,5}.at n=15A119039
- Triangular numbers composed of digits {0,2,5}.at n=5A119051
- Triangular numbers composed of digits {0,3,5}.at n=6A119061
- Triangular numbers composed of digits {0,4,5}.at n=9A119071
- Triangular numbers composed of digits {0,5,6}.at n=12A119079
- Triangular numbers composed of digits {0,5,7}.at n=5A119081
- Triangular numbers composed of digits {0,5,8}.at n=3A119083
- Triangular numbers composed of digits {0,5,9}.at n=6A119085
- Numbers k such that k and k^2 use only the digits 0, 2 and 5.at n=32A136910
- Smallest value of k for which 6*k+1 divides the subset of centered hexagonal terms included in A177019 that admit only factors like 6*k+1.at n=4A178509
- Triangular numbers having only 1 or 2 different digits in base 10.at n=40A213516
- Triangular numbers whose nonzero digits are all the same.at n=16A352057
- Kaprekar numbers that are the concatenation of two equal numbers.at n=14A381917