18290

Appears in sequences

• Number of base 30 n-digit numbers with adjacent digits differing by four or less.at n=4A126525
• a(n) = floor(n^3/3).at n=38A131476
• Numbers k such that k and k+1 have 4 distinct prime factors.at n=21A140078
• Number of (w,x,y,z) with all terms in {1,...,n} and 3*w = x+y+z.at n=38A212069
• Number of ways to write highly composite numbers (A002182(n)) as the difference of two primes, both <= 2*A002182(n).at n=36A228945
• Nonnegative numbers k such that 3*k + 2 is a cube.at n=12A287335
• a(n) is the maximum value of the quartet index of a bifurcating rooted tree with n leaves.at n=32A300445
• Numbers k such that k and k+1 are the product of exactly four distinct primes.at n=11A318896
• Numbers k such that k and k+1 each have at least 4 distinct prime factors.at n=21A321504
• a(1) = 27846; thereafter a(n+1) = a(n) # n, where # is an operation that cycles through division, addition, subtraction and multiplication.at n=14A327962
• a(1) = 1; a(n) = -Sum_{k=1..n} a(k/gcd(n,k)).at n=34A343762
• a(n) is the index of the smallest n-gonal pyramidal number with exactly n distinct prime factors.at n=8A359015