139968

Appears in sequences

• a(n) = a(n-1)*a(n-2)*a(n-3) with a(1)=1, a(2)=2 and a(3)=3.at n=6A000308
• n is equal to the number of 4s in all numbers <= n written in base 6.at n=20A014892
• Numbers of form 3^i*8^j, with i, j >= 0.at n=39A025615
• Ratios of successive terms are 3, 2, 3, 2, 3, 2, 3, 2, ...at n=13A026532
• a(n) = 6*a(n-2), starting with 1, 3, 9.at n=13A026565
• Dan numbers: numbers m of the form 2^j * 3^k such that m +- 1 are twin primes.at n=10A027856
• Numbers k that divide the (right) concatenation of all numbers <= k written in base 9 (most significant digit on left).at n=34A029454
• a(n) = k, where k/(product of digits of k) is least possible integer for k with n digits.at n=5A034686
• Triangle whose (i,j)-th entry is binomial(i,j)*3^(i-j)*6^j.at n=26A038224
• Triangle whose (i,j)-th entry is binomial(i,j)*6^(i-j)*3^j.at n=22A038257
• Triangular matrix arising in enumeration of catafusenes, read by rows.at n=62A038763
• Numbers m such that m divides (product of digits of m) * (sum of digits of m).at n=24A049101
• Euler totient function (A000010) of 2^n - 1.at n=17A053287
• Number of step shifted (decimated) sequences using a maximum of three different symbols.at n=11A056372
• Duplicate of A027856.at n=10A059961
• a(n) is the least k>n such that k*n = (product of digits of k) * (sum of digits of k), or 0 if no such k exists.at n=3A066156
• Smallest k-almost prime between twin primes (for k >= 2).at n=11A068525
• Numbers n such that n=phi(n)*core(n) where phi(x) is the Euler totient function and core(x) the squarefree part of x (the smallest integer such that x*core(x) is a square).at n=30A069185
• 5-full numbers: if a prime p divides k then so does p^5.at n=35A069492
• 6-full numbers: if p divides n then so does p^6.at n=23A069493