20440

Appears in sequences

• sigma_3(n): sum of cubes of divisors of n.at n=26A001158
• Number of equivalence classes with primitive period n of base 3 necklaces, where necklaces are equivalent under rotation and permutation of symbols.at n=12A002075
• Expansion of 8-dimensional cusp form.at n=27A002408
• Fourier coefficients of E_{infinity,4}.at n=27A007331
• a(n) = Sum_{ d >= 1, d divides n} (-1)^(n-d)*d^3.at n=26A008457
• Numerator of sum of -3rd powers of divisors of n.at n=26A017669
• Numbers n such that sigma(phi(n)) = n.at n=7A018784
• Number of 4-unbalanced strings of length n (=2^n-A027559(n)).at n=15A027561
• Base 3 digits are, in order, the first n terms of the periodic sequence with initial period 1,0,0.at n=9A033139
• Base 9 digits are, in order, the first n terms of the periodic sequence with initial period 3,1,0.at n=4A037665
• a(n) = sigma_3(2*n+1).at n=13A045823
• Sum of cubes of odd divisors of n.at n=26A051000
• a(n) = n^3 + n^2 + n + 1.at n=27A053698
• a(n) = Sum_{k divides n} (n/k)^k.at n=26A055225
• Intrinsic 10-palindromes: n is an intrinsic k-palindrome if it is a k-digit palindrome in some base.at n=19A060947
• Numbers k such that sigma(phi(k)) == 0 (mod k).at n=8A067144
• Numbers n such that sigma(reverse(n)) = phi(n).at n=14A070856
• a(n) = Sum_{k=0..n} S(k), where S(n) are the tribonacci generalized numbers A001644.at n=15A073728
• Numbers of the form (3^{mr}-1)/(3^r-1) for positive integers m, r.at n=22A076270
• a(n) = -Sum_{d|n} (-n/d)^d.at n=26A076717