97020

Appears in sequences

• Number of 4-block ordered bicoverings of an unlabeled n-set.at n=23A060091
• Triangular numbers which are products of triangular numbers larger than 1.at n=40A068143
• Triangular numbers which are 8-almost primes.at n=11A076582
• Smallest triangular number divisible by exactly n triangular numbers.at n=18A076983
• a(n) = smallest number which can be expressed as sum of d consecutive positive integers in exactly n ways (where d>0 is a divisor of the number).at n=22A082637
• a(n) = n^2 * (n^2 - 1)/2.at n=20A083374
• Triangular numbers that set a new record for number of triangular divisors.at n=11A084260
• Triangular numbers > 0 with a prime signature that has not occurred earlier.at n=40A085076
• Triangular numbers in which the sum of the external digits equals the sum of the internal digits.at n=24A088289
• Triangle read by rows giving the coefficients of formulas generating each variety of S1(n,k) (unsigned Stirling numbers of first kind). The p-th row (p>=1) contains T(i,p) for i=1 to 2*p, where T(i,p) satisfies Sum_{i=1..2*p} T(i,p) * C(n,i).at n=40A094216
• Structured small rhombicosidodecahedral numbers.at n=17A100148
• Combinatorial triangle !n. This table read by rows gives the coefficients of general sum formulas of n-th left factorials (A003422). The k-th row (k>=1) contains T(i,k) for i=1 to 2*k and k=1 to n-2, where T(i,k) satisfies !n = n + Sum_{k=1..n-2} Sum_{i=1..2*k} T(i,k) * C(n-k-1,i).at n=40A102639
• Number triangle T(n,k) = C(n,n-k)*C(n+1,n-k).at n=59A103371
• Values of y in x^2 - 49 = 2*y^2.at n=17A106526
• Fifth column of triangle A103371 (without leading zeros).at n=6A134287
• The least number k such that there are n different representations of k as the difference of two positive triangular numbers.at n=35A136108
• Numbers with exactly 5 distinct prime divisors {2,3,5,7,11}.at n=29A147572
• Binomial(n-k-1,k) * binomial(n-k,k+1) where k = ceiling(n/4).at n=15A171006
• Triangle T(n, k) = (2*k/(k+1))*binomial(n-1, k)*binomial(n+1, k) with T(n, 0) = T(n, n) = 1, read by rows.at n=60A174117
• Let T(n) = n(n+1)/2 be the n-th triangular number (A000217); a(n) = T(8T(n)).at n=10A185096