222222111111
domain: N
Appears in sequences
- a(n) = triangular number whose index is n concatenated n times.at n=5A077695
- Let n = abc... where a,b,c ... are the digits. Then a(n) = least multiple of n of the form aaa...bbb...ccc..., with each digit having the same frequency f > 1; or 0 if no such number exists.at n=20A110732
- Triangular numbers whose representation is made of nontrivial runs of identical digits.at n=16A116055
- Triangular numbers composed of digits {0,1,2}.at n=20A119033
- Triangular numbers composed of digits {1,2,3}.at n=16A119097
- Triangular numbers composed of digits {1,2,4}.at n=10A119099
- Triangular numbers composed of digits {1,2,5}.at n=24A119101
- Triangular numbers composed of digits {1,2,6}.at n=25A119103
- Triangular numbers composed of digits {1,2,7}.at n=15A119105
- Triangular numbers composed of digits {1,2,8}.at n=19A119107
- Triangular numbers composed of digits {1,2,9}.at n=9A119109
- Triangular numbers obtained as the concatenation of 2*k and k.at n=17A226742
- Smallest triangular number ending in n ones.at n=5A227218
- Triangular numbers of the form 2..21..1; n_times 2 followed with n_times 1; n >= 1.at n=5A319170