66666666666
domain: N
Appears in sequences
- a(n) = 6*(10^n - 1)/9.at n=11A002280
- Repdigit + 1 is prime.at n=13A028988
- Numbers n such that n and 2n-1 are both palindromes.at n=15A069882
- Worthless numbers: numbers without h, o, r, t, or w.at n=23A073419
- Number of Fibonacci numbers F(k), k <= 10^n, which end in 2.at n=11A073548
- Number of Fibonacci numbers F(k), k <= 10^n, which end in 6.at n=11A073549
- Largest term in periodic part of continued fraction expansion of square root of n-th repunit.at n=21A096487
- Numbers k such that the k-th triangular number contains only digits {1,2,3}.at n=29A119098
- Numbers k such that the k-th triangular number contains only digits {1,2,4}.at n=19A119100
- Numbers k such that the k-th triangular number contains only digits {1,2,7}.at n=23A119106
- Numbers k such that the k-th triangular number contains only digits {1,2,9}.at n=17A119110
- Numbers k such that k and k^2 use only the digits 3, 4, 5 and 6.at n=10A137120
- Numbers k such that k and k^2 use only the digits 3, 4, 5, 6 and 8.at n=26A137122
- A109613(n)-fold concatenation of A008619(n).at n=10A180115
- Repdigit numbers with repdigit digital sum.at n=29A201061
- Conversion to octal of the binary expansion given by the first n terms of the period-3 sequence A011655 (repeat 0, 1, 1).at n=33A289006
- An explicit example of an infinite sequence with a(1)=1 and, for n >= 2, a(n) and S(n) = Sum_{i=1..n} a(i) have no digit in common.at n=21A308900