137256

Appears in sequences

• n is equal to the number of 1's in all numbers <= n written in base 7.at n=4A014887
• a(n) = (n-1)*(2*n-1)*(3*n-1).at n=29A033594
• Triangle read by rows: T(n,k) = (n+1,k)-th element of (M^7-M)/6, where M is the infinite lower Pascal's triangle matrix, 1<=k<=n.at n=22A096041
• a(0) = 0; a(n) = 7*a(n-1) + 7.at n=6A104896
• a(n) = (n^7 - n)/6.at n=7A108495
• Triangle by rows T(n,k), showing the number of meanders with length (n+1)*6 and containing (k+1)*6 Ls and (n-k)*6 Rs, where Ls and Rs denote arcs of equal length and a central angle of 60 degrees which are positively or negatively oriented.at n=34A197655
• a(n) = (n^n - n)/(n - 1).at n=5A226238
• a(n) = n^6 + n^5 + n^4 + n^3 + n^2 + n.at n=7A228290
• Smallest positive multiple of n whose base-7 representation contains only 0's and 1's.at n=41A244958
• Least k such that p = k^2 + 1 and q = (k+2n)^2 + 1 are prime numbers with q - p square.at n=18A339007
• a(n) = Sum_{k=0..n} n^k * |(n - k | k)|, where (a | b) denotes the Kronecker symbol.at n=7A367546