36720

Appears in sequences

• Infinitary perfect numbers.at n=3A007357
• Infinitary multi-perfect numbers.at n=5A007358
• tan(arcsin(x)+sin(x))=2*x+16/3!*x^3+522/5!*x^5+36720/7!*x^7...at n=3A012914
• Let sigma_m (n) be result of applying sum-of-divisors function m times to n; call n (m,k)-perfect if sigma_m (n) = k*n; sequence gives the (4,k)-perfect numbers.at n=53A019293
• a(n) = n*(n + 1)*(n + 2)*(n + 3)/2.at n=15A033486
• Triangle read by rows. A generalization of unsigned Lah numbers, called L[4,1].at n=52A048854
• Expansion of e.g.f. (1-x)/(1-3*x-2*x^2+2*x^3).at n=5A052674
• Infinitary harmonic numbers: harmonic mean of infinitary divisors is an integer.at n=14A063947
• Even legs of Pythagorean triangles whose other leg and hypotenuse are both prime.at n=14A067755
• 4-infinitary perfect numbers: numbers k such that 4-infinitary-sigma(k) = 2*k.at n=2A074849
• UO-sigma multiperfect numbers: n such that A069184(n)/n is an integer.at n=5A092356
• Number of irregular primes less than e^n.at n=13A105457
• Triangle read by rows: T(n,k) is number of paths from (0,0) to (3n,0) that stay in the first quadrant (but may touch the horizontal axis), consisting of steps u=(2,1),U=(1,2), or d=(1,-1) and have k pyramids (a pyramid is a sequence u^pd^p or U^pd^(2p) for some positive integer p, starting at the x-axis).at n=40A108445
• a(n) = binomial(n,4) - binomial(floor(n/2),4) - binomial(ceiling(n/2),4).at n=33A111385
• a(n) = C(1+n,1) * C(2+n,1) * C(4+n,2).at n=14A112415
• Egyptian fraction representation for the cube root of 46.at n=3A132521
• a(n) = n*(3*n-1)*n!/2.at n=5A138782
• Pythagorean triangle side lengths triples with two lengths prime.at n=42A140391
• a(n) is smallest number with divisors which are congruent to 1, 2, ..., n-1 mod n.at n=31A140539
• Number of permutations of floor(i*5/4), i=0..n-1, with all sums of 2 through 4 adjacent terms respectively unique.at n=8A147902