33336636

Appears in sequences

• Numbers k such that the k-th triangular number contains only digits {0,5,6}.at n=22A119080
• Numbers k such that the k-th triangular number contains only digits {2,5,6}.at n=18A119165
• Numbers k such that the k-th triangular number contains only digits {3,5,6}.at n=23A119187
• Numbers k such that the k-th triangular number contains only digits {4,5,6}.at n=21A119203
• Numbers k such that the k-th triangular number contains only digits {5,6,7}.at n=12A119219
• Numbers k such that the k-th triangular number contains only digits {5,6,8}.at n=15A119221
• Numbers k such that the k-th triangular number contains only digits {5,6,9}.at n=15A119223
• Numbers k such that the triangular number k*(k+1)/2 has 2 different digits in base 10.at n=45A213518
• a(n) = ( (-1)^n * Sum_{k=0..n-2} (-1)^k*10^(2^k) + 10^(2^(n-1)) - ((-1)^n+3)/2 )/3.at n=3A325907