54421

Properties

Appears in sequences

• a(1) = 1; for n>1, a(n) = the largest prime divisor of the number C(n) formed from the concatenation of n, n-1, n-2, n-3, ... down to 1.at n=9A075021
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 0, 1), (-1, 1, -1), (0, 1, 1), (1, -1, 0)}.at n=11A148346
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 1), (-1, 0, 1), (-1, 1, -1), (0, 1, 1), (1, -1, 0)}.at n=11A148347
• A general recursion triangle with third part a power triangle:m=3; Power triangle: f(n,k,m)=If[n*k*(n - k) == 0, 1, n^m - (k^m + (n - k)^m)]; Recursion: A(n,k,m)=(m*(n - k) + 1)*A(n - 1, k - 1, m) + (m*k + 1)*A(n - 1, k, m) + m*f(n, k, m)*A(n - 2, k - 1, m).at n=29A157630
• A general recursion triangle with third part a power triangle:m=3; Power triangle: f(n,k,m)=If[n*k*(n - k) == 0, 1, n^m - (k^m + (n - k)^m)]; Recursion: A(n,k,m)=(m*(n - k) + 1)*A(n - 1, k - 1, m) + (m*k + 1)*A(n - 1, k, m) + m*f(n, k, m)*A(n - 2, k - 1, m).at n=34A157630
• a(n) is the number of digits in the decimal representation of the smallest power of 6 that contains n consecutive identical digits.at n=10A217188
• Terms k of A112998 such that k+2 is nonsquarefree.at n=29A328160
• Numbers m such that numbers m, m + 1, m + 2 and m + 3 have k, 2k, 3k and 4k divisors respectively.at n=33A340157
• Primes p such that p, p + 1, p + 2 and p + 3 have 2, 4, 6 and 8 divisors respectively.at n=3A340871
• Prime numbers such that the product of their digits equals twice the number of their digits times the sum of their digits.at n=5A343701
• Numbers k such that d(k) < d(k+1) < d(k+2) < d(k+3) < d(k+4), where d(n) is the number of divisors of n.at n=10A364717
• Prime numbersat n=5538