90270

Appears in sequences

• Numbers n such that the number of primes between n^2 and (n+1)^2 = the number of primes between n and Reverse(n) (inclusive).at n=29A074817
• The number of tilings of an equilateral triangle of side length n with k lozenges and n^2 - 2*k unit triangles. Triangle T(n, k) with n >= 1 and 0 <= k <= n*(n + 1)/2, read by rows.at n=29A273464
• Numbers k such that A(k+1) = A(k) + 3, where A() = A005100() are the deficient numbers.at n=34A317046
• Number of tilings of an equilateral triangle of side length n with unit triangles (of side length 1) and exactly four unit "lozenges" or "diamonds" (also of side length 1).at n=5A326369
• Those primitive elements of A337386 that have exactly one primitive nondeficient divisor (A006039).at n=35A341604
• Dirichlet g.f.: Product_{k>=2} 1 / (1 - k^(-s))^binomial(k+3,4).at n=33A344204
• Least number k such that k and k+2 both have exactly 2n divisors, or -1 if no such number exists.at n=23A356766