36992

Appears in sequences

• Coordination sequence for 4-dimensional cubic lattice (points on surface of 4-dimensional cross-polytope).at n=24A008412
• Expansion of e.g.f. tan(x)*tan(tan(x)), even powers only.at n=4A009750
• Coordination sequence for C_4 lattice.at n=12A019560
• a(n) = n + (n+1)^2 + (n+2)^3.at n=31A027620
• Least number x such that gcd(phi(x), sigma(x)) = n.at n=16A073815
• Smallest number m such that GCD(a+b,a-b) = n, where a = sigma(m) and b = phi(m).at n=16A077102
• Duplicate of A073815.at n=16A077104
• Consider the mapping f(a/b) = (a^2+b^2)/(a^2-b^2) from rationals to rationals. Starting with 2/1 (a=2, b=1) and applying the mapping to each new (reduced) rational number gives 2/1, 5/3, 17/8, 353/225, ... Sequence gives values of the denominators.at n=4A081466
• Least x=a(n) such that product of common prime-divisors [without multiplicity] of sigma(x) and phi(x) equals n; or 0 if n is not a squarefree number or if no such x exists. Among indices n only squarefree numbers arise because multiplicity of prime factors is ignored.at n=16A082057
• Fifth column (k=4) of triangle A084938.at n=7A090319
• Eighth diagonal (m=7) of triangle A084938; a(n) = A084938(n+7,n) = (n^7 + 63*n^6 + 1855*n^5 + 34125*n^4 + 438424*n^3 + 3980172*n^2 + 20946960*n)/5040.at n=4A090393
• a(1)=1, a(n) = n*a(floor(n/2)).at n=33A098844
• Integers that are Rhonda numbers to base 6.at n=9A100969
• a(n) is the least k such that k-n and k are adjacent powerful numbers.at n=28A103955
• Number of subsets of {1,2,....,n} with an arithmetic mean that is an integer and also a divisor of n.at n=26A114976
• Denominators of the continued fraction convergents of the decimal concatenation of the even natural numbers.at n=7A128843
• E.g.f. satisfies: A(x) = x + sinh( A(x) )^2.at n=5A143136
• a(n) = n*(n+2)^2.at n=32A152619
• Number of collinear point-triples in the n X n X n cube.at n=7A157882
• a(n) = n^2*(n+1)^2/2.at n=16A163102