115440

Appears in sequences

• a(n) = floor(n(n-1)(n-2)(n-3)/19).at n=40A011929
• Triangular numbers which are 8-almost primes.at n=13A076582
• Triangular numbers obtained as a concatenation of successive terms of A081847.at n=25A082235
• Triangular numbers > 0 with a prime signature that has not occurred earlier.at n=42A085076
• Triangular numbers that are sandwiched between two semiprimes; or triangular numbers t such that t-1 and t+1 are both semiprime.at n=24A121898
• a(n) = Sum_{k=0..[n/2]} C(2^k + n-2k-1, n-2k); equals the antidiagonal sums of triangle A137153.at n=14A137155
• Triangular numbers which are sums of 4 consecutive primes.at n=14A173420
• Triangular numbers k whose divisors can be partitioned into three disjoint sets whose sums are all sigma(k)/3.at n=36A206025
• Number of (w,x,y,z) with all terms in {1,...,n} and |w-x| >= w + |y-z|.at n=31A212714
• Number of ways of writing n as the sum of 10 triangular numbers from A000217.at n=22A226254
• Refactorable triangular numbers.at n=25A272524
• Coefficient of x^(2*n) in (-1 + Product_{k>=1} 1 / (1 + x^k))^n.at n=13A341265
• Difference between 4*A001590(n+2) and A075092(n).at n=19A349700
• Triangular numbers that are sandwiched between two squarefree semiprimes.at n=22A375384