64260

Appears in sequences

• Unitary harmonic numbers (those for which the unitary harmonic mean is an integer).at n=21A006086
• a(n) = floor( n*(n-1)*(n-2)*(n-3)/22 ).at n=36A011932
• n written in fractional base 8/6.at n=40A024648
• a(n) = binomial(n+4,4)*(2*n+1).at n=13A051880
• Partial sums of A051836.at n=13A051923
• Denominator of sum of first n terms of the series 1/3 + 1/8 + 1/24 ... in which the denominators are one less than a perfect square that cannot otherwise be written as a power (cf. A062757, A037450).at n=19A062834
• a(n) = C(2n-1,n-1) mod n^3.at n=41A099907
• Numbers with prime factorization p*q*r*s^2*t^3 (where p, q, r, s, t are distinct primes).at n=10A190111
• Sum_{0<j<k<=n} s(k)-s(j), where s(j)=A002620(j) is the j-th quarter-square.at n=33A206806
• Number of (w,x,y,z) with all terms in {1,...,n} and w>2x and y>=3z.at n=36A212519
• Triangular array read by rows: T(n,k) is the number of simple labeled graphs with n vertices and k components such that each vertex has even degree; n >= 1, 1 <= k <= n.at n=39A228550
• a(n) = binomial(2*c-1, c-1) (mod c^3), where c is the n-th composite.at n=27A244214
• Numbers k such that k = Sum_{i=1..j} (d_i mod d), where d_i are their aliquot parts and d is one of them.at n=20A265646
• Expansion of Product_{k>=1} 1/(1 - (4*k-3)*x^(4*k-3)).at n=33A265830
• a(n) = binomial(n+3, 3)*(1 + binomial(n+2, 3)/4).at n=13A291288
• Exponential (2,4)-perfect numbers: numbers m such that esigma(esigma(m)) = 4m, where esigma(m) is the sum of exponential divisors of m (A051377).at n=30A328133
• Numbers whose divisors have a harmonic mean with a denominator 2.at n=25A348411
• Numbers that are both unitary and nonunitary harmonic numbers.at n=3A348923
• Unitary arithmetic numbers k whose mean unitary divisor is a unitary divisor of k.at n=8A353039
• Indices of records of A138705.at n=36A362285