20413

Appears in sequences

• Positive numbers k such that k and 2*k are anagrams in base 6 (written in base 6).at n=20A023064
• a(n) = a(n-1)+ a(round(2*(n-1)/3)) +a(round((n-1)/3)) starting a(1)=1.at n=35A033498
• a(n) = Sum_{ d divides n } (n/d)^(3d).at n=8A073706
• a(n) = prime(n)*prime(n+2).at n=32A090076
• a(n) = n^3 + n^2 + 1.at n=27A098547
• The numerator of determinant of n X n matrix with elements M[i,j] = 1/(Prime[i] + Prime[j]), i,j=1..n.at n=35A120270
• The numerator of determinant of n X n matrix with elements M[i,j] = 1/(Prime[i] + Prime[j]), i,j=1..n.at n=36A120270
• The numerator of determinant of n X n matrix with elements M[i,j] = 1/(Prime[i] + Prime[j]), i,j=1..n.at n=37A120270
• 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), (1, 0, -1), (1, 1, 1)}.at n=8A149626
• a(n) = 729*n + 1.at n=27A158397
• a(n) = 28*n^2 + 1.at n=27A158556
• a(n) = prime(n) times the n-th nonnegative noncomposite.at n=34A176098
• Numbers whose digits are a permutation of [0,...,n] and which contain the product of any two adjacent digits as a substring.at n=19A203569
• In base 5, numbers n which have 5 distinct digits, do not start with 0, and have property that the product (written in base 5) of any two adjacent digits is a substring of n.at n=3A210016
• Let an integer with k+1 digits as n = d(k)*10^k + d(k-1)*10^(k-1) + ... + d(0)*10^0 and consider the transform T(n) = k*10^d(k) + (k-1)*10^d(k-1) + ... + 0*10^d(0). a(n) gives the fixed points of the transform T(n).at n=20A226767
• S_5 sequence in partition of integers > 1 described in A240521.at n=39A240522
• Semiprimes whose prime factors are of equal binary length and which differ from each other in exactly three bit positions.at n=36A261075
• Sequence of pairwise relatively prime numbers of class P_4 (see comment in A275246).at n=16A275248
• Sum of cubes of nonprime divisors of n.at n=26A279290
• Integers x such that [f(0), f(f(0)), ..., f(...f(0)...)] is a permutation of [0, 1, ..., k-1], where k is the number of digits in x and f(a) denotes the 0-based index of the first occurrence of the substring a in x.at n=17A307620