51360

Appears in sequences

• Triangular numbers k*(k+1)/2 such that A068865(k) = k*(k+1)/2.at n=26A068866
• Triangular numbers which are 8-almost primes.at n=7A076582
• Triangular numbers which are the sum of distinct double factorials (A006882).at n=27A115650
• (n-1)-st elementary symmetric function of {1, 2, 2, 3, 3, 4, 4, 5, 5, ..., floor(1+n/2)}.at n=8A203152
• a(n) = 4*n^3 + 5*n^2 + 2*n + 1.at n=23A204674
• Triangular numbers k whose divisors can be partitioned into three disjoint sets whose sums are all sigma(k)/3.at n=24A206025
• Number of (w,x,y,z) with all terms in {1,...,n} and median=mean.at n=30A212133
• Triangular numbers which are an average of four consecutive primes.at n=26A226196
• a(n) = smallest k such that prime(n) is the n-th largest divisor of k.at n=27A226326
• Numbers n such that there exists an x!=n that makes {x,x,n} an amicable multiset.at n=9A259303
• Refactorable triangular numbers.at n=18A272524
• Number of n X 2 0..1 arrays with each 1 adjacent to 2 or 3 king-move neighboring 1s.at n=10A295979
• Numbers that have exactly 7 representations as a k-gonal number, P(n,k) = n*((k-2)*n - (k-4))/2, k and n >= 3.at n=6A321157
• Sum of the sixth largest parts of the partitions of n into 10 parts.at n=50A326593
• Number of binary words of length n that avoid abelian 4th powers circularly.at n=39A334831
• Numbers that start a run of four consecutive triangular numbers with four distinct prime factors.at n=10A349773
• Positive triangular numbers such that the two numbers before it and the two numbers after it are squarefree.at n=39A374503
• Numbers k for which sigma(k) >= 2*k and (sigma(k) - 2*k) AND k = k, where AND is bitwise-and, A004198.at n=34A388026
• Convolution of A000041 and A237271.at n=31A390878