70200

Appears in sequences

• [ n(n-1)(n-2)(n-3)/7 ].at n=28A011917
• a(n) = n*(n+1)*(n+2)*(n+3)/6.at n=24A033488
• Numbers n divisible by exactly four nontrivial permutations (rearrangements) of the digits of n.at n=2A090059
• Averages of twin primes such that the sum of the lower, average and upper parts of the twin primes are averages of other twin primes.at n=24A132929
• a(n) = (9/2)*(n-1)*(n-2)*(n-3).at n=26A134171
• Expansion of 104*x^2 / (-x^3+675*x^2-675*x+1).at n=2A157874
• Number of subsets S of {1,2,3,...,n} with the property that if x is a member of S then at least one of x-2 and x+2 is also a member of S.at n=20A172020
• Numbers with prime factorization pq^2r^3s^3.at n=4A190320
• Central binomial coefficient CB(n) purged of all primes exceeding (n+1)/2.at n=44A212791
• Total number of components of the fruitful tree A_n(d_n).at n=8A216811
• The Wiener index of the Kneser graph K(n,2) (n>=5).at n=22A228306
• Number of ways to place 2 points on a triangular grid of side n so that they are not adjacent.at n=25A239568
• Integer areas A of integer-sided triangles such that the length of the circumradius is a prime number.at n=32A256629
• Imaginary part of (n + i)^4.at n=26A272871
• a(n) = 54*n^2 + 6*n.at n=36A277990
• Heinz numbers of integer partitions whose sum of reciprocals squared is an integer.at n=35A318588
• Coreful 3-abundant numbers: numbers k such that csigma(k) > 3*k, where csigma(k) is the sum of the coreful divisors of k (A057723).at n=23A340109
• G.f. A(x) satisfies: A(x) = 1 + x + x^2 + x^3 + x^4 + x^5 * A(x)^3.at n=24A346735
• For n > 1, if n appears in the sequence then a(n) = lastindex(n), where lastindex(n) is the index of the last appearance of n. Otherwise a(n+1) = a(n)/(n+1) if (n+1)|a(n), otherwise a(n)*(n+1), a(1) = 1 and a(2) = 1*2.at n=26A362332
• Let d(1)<d(2)<...<d(q) denote the divisors of an integer k. a(n) = k is the smallest k such that the sum of its first n divisors, s = d(1) + ... + d(n), is also a divisor of k.at n=44A375574