25410

Appears in sequences

• Number of rooted trees with 4 nodes of disjoint sets of labels with union {1..n}. If a node has an empty set of labels then it must have at least two children.at n=6A005174
• Area of more than one Pythagorean triangle.at n=21A009127
• Expansion of Product_{m>=1} 1/(1 - m*q^m)^6.at n=7A022730
• Positive numbers k such that k and 2*k are anagrams in base 7 (written in base 7).at n=7A023068
• a(n) = (n/(n+1)) * lcm(1,2,...,n+1).at n=10A025558
• Triangle T(n,k) of number of minimal 4-covers of a labeled n-set that cover k points of that set uniquely (k=4,..,n).at n=7A057965
• a(1)=1, a(2)=2; thereafter, a(n) is the smallest number m not yet in the sequence such that every prime that divides a(n-1) also divides m.at n=33A060735
• a(n) = lcm(1,...,n) - (product of primes <= n).at n=10A068510
• a(n) = lcm(1,...,n) - (product of primes <= n).at n=11A068510
• Integers k such that omega(k) = omega(k-1) + omega(k-2) + omega(k-3), where omega(n) is the number of distinct prime factors of n.at n=18A076252
• a(n) is the smallest number k such that r*k + 1 is prime for all r = 1 to n.at n=5A088250
• Equal count of primes congruent to 1 mod 4 and 3 mod 4 associated with primes in A007351 (the zero beginning the sequence indicates the prime 2).at n=34A092198
• Triangle read by rows: T(n,k) is the number of rooted trees with k nodes which are disjoint sets of labels with union {1..n}. If a node has an empty set of labels then it must have at least two children.at n=39A094262
• Triangle read by rows: T(n,k) is the number of noncrossing trees with n edges in which the leftmost child of the root has degree k.at n=50A101401
• a(n) is a non-palindromic composite located between twin primes whose reverse, which is less than it, is also located between twin primes.at n=19A103741
• a(n) = 4*(n^1 + 1!)*(n^2 + 2!)*(n^3 + 3!)*(n^4 + 4!)/4!.at n=3A131683
• Riordan matrix T from A084358 (lists of sets of lists) inverse to the Riordan matrix TI = 2I-A129652 formed from A000262 (number of sets of lists) and reciprocal under a partition transform.at n=40A133289
• Numbers with exactly 5 distinct prime divisors {2,3,5,7,11}.at n=10A147572
• a(0)=1. For n>=1, write n in binary. Let b(n,m) be the length of the m-th run of 0's or 1's, reading right to left. Then a(n) = product{m=1 to M} p(m)^b(n,m), where p(m) is the m-th prime, and M is the number of runs of 0's and 1's in binary n.at n=53A163755
• Number of permutations of 1..n with the sequence of sums of 2 adjacent elements having exactly 2 maxima.at n=5A179711