108927

Appears in sequences

• Expansion of 1/((1-5x)(1-6x)(1-7x)(1-11x)).at n=4A028168
• Reversion of g.f. (with constant term included) for partition numbers.at n=20A066398
• Matrix inverse of A100862.at n=50A107102
• Odd n such that 2*phi(n) < n, but there does not exist an even k < n with phi(k) = phi(n).at n=13A118700
• Number of (w,x,y,z) with all terms in {1,...,n} and w > x < y >= z.at n=27A212501
• Odd numbers n such that 2n/sigma(n) - 1 = 1/x for some positive integer x.at n=29A222263
• Odd integers k such that sigma(k)^2 is divisible by k.at n=4A263983
• Numbers n such that the set of prime divisors of n is equal to the set of prime divisors of sum of proper divisors of n while n is not in A027598.at n=19A286876
• Odd numbers k such that the set of distinct prime divisors of k is equal to the set of distinct prime divisors of the sum of proper divisors of k.at n=0A286884
• Numbers n=2*k-1 where Sum_{j=1..k} (-1)^(j+1) * d(2*j-1) achieves a new negative record, with d(n) = number of divisors of n (A000005).at n=26A318738
• Indices k at which record low values of the ratio A046530(k)/k occur.at n=39A330695
• Numbers k such that k and k+1 have different (ordered) prime signatures and d_3(k) = d_3(k+1), where d_3 is A007425.at n=9A333057
• Odd numbers k such that rad(k) divides sigma(k).at n=15A336554
• a(n) is the index of the smallest square pyramidal number divisible by exactly n square pyramidal numbers.at n=27A359095
• Number of irreducible conic curves containing 6 points of a cyclic order n-torsion subgroup of an elliptic curve.at n=34A379920
• Number of integer partitions of n having more than one permutation with all equal run-lengths.at n=48A383090
• Odd numbers k for which A000005(2*k) >= A017665(2*k), where A000005 is the number of divisors function, and A017665 is the numerator of the abundancy ratio, sigma(k)/k.at n=12A388277