222111
domain: N
Appears in sequences
- Doubly triangular numbers: a(n) = n*(n+1)*(n^2+n+2)/8.at n=36A002817
- Iterated triangular numbers with seed 8.at n=3A050536
- Triangular numbers that contain exactly 2 different digits.at n=23A062691
- Triply triangular numbers.at n=8A064322
- Triangular numbers in which neighboring digits differ at most by 1. Allowed neighbors of 9 are 0, 8 and 9.at n=21A068149
- Triangular numbers whose external digits as well as internal digits form triangular numbers.at n=32A077368
- Triangular numbers whose representation is made of nontrivial runs of identical digits.at n=4A116055
- Triangular numbers for which the sum of the digits is a square.at n=31A117404
- Triangular numbers composed of digits {0,1,2}.at n=9A119033
- Triangular numbers composed of digits {1,2,3}.at n=8A119097
- Triangular numbers composed of digits {1,2,4}.at n=3A119099
- Triangular numbers composed of digits {1,2,5}.at n=11A119101
- Triangular numbers composed of digits {1,2,6}.at n=8A119103
- Triangular numbers composed of digits {1,2,7}.at n=7A119105
- Triangular numbers composed of digits {1,2,8}.at n=7A119107
- Triangular numbers composed of digits {1,2,9}.at n=4A119109
- Triangular numbers having only 1 or 2 different digits in base 10.at n=30A213516
- List of words over {1,2} with equal numbers of 1's and 2's.at n=27A214218
- Triangular numbers obtained as the concatenation of 2*k and k.at n=4A226742
- If x is in the sequence then so are x^2 and x(x+1)/2.at n=37A241241