31530

Appears in sequences

• Least k such that k*(Mersenne_prime(n)^2) + 1 is prime.at n=21A098819
• Triangle of coefficients of polynomials u(n,x) jointly generated with A210861; see the Formula section of A210861.at n=39A210860
• Numbers k such that k^2 +/- (k-1) and (k-1)*k^2 +/- 1 are all primes.at n=30A239326
• Number of numbers k in interval [(p_n)^2+1, (p_n)^4] for which lpf(k-3)>lpf(k-1)>=p_n, where p_n=prime(n) and lpf = A020639.at n=10A243803
• Take apart the sides of each of the integer-sided scalene triangles with perimeter n (at their vertices) and rearrange them orthogonally in 3-space so that their endpoints coincide at a single point. a(n) is the total surface area of all rectangular prisms enclosed in this way.at n=40A308235
• Integers n such that the digit set of n^2 is {0,1,4,9}.at n=31A317579