21315

Appears in sequences

• a(n) = (4*n+1)*(4*n+3).at n=36A001539
• a(n) = 49*(n-1)*(n-2)/2.at n=28A027469
• Numbers k such that k | p(k) - q(k) where p(k) = partition numbers (A000041) and q(k) = partition numbers into distinct parts (A000009).at n=9A056873
• Numbers n such that n+1 and phi(n)+1 are both perfect squares.at n=21A089952
• Chebyshev U(n,x) polynomial evaluated at x=73 = 2*6^2+1.at n=2A097728
• Numbers such that the sum of the factorials of the digits of the fifth power is a square.at n=25A126078
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 0, 1), (-1, 1, -1), (1, 0, 0), (1, 0, 1)}.at n=8A150309
• a(n) = binomial(n+1,2)*7^2.at n=29A162942
• Product of two consecutive odd numbers k, k+2 such that (k*(k+2))+-2 are primes.at n=8A174383
• a(n) = AR(n) is the total number of aperiodic k-reverses of n.at n=20A180322
• Numbers n such that (n^6 + 1091)/4 is prime.at n=12A181112
• a(n) = (a(n-1) - a(n-3))*7^((1+(-1)^n)/2) with a(6)=5, a(7)=4, a(8)=22.at n=12A215139
• Number of partitions p of n such that median(p) > multiplicity(max(p)).at n=39A240210
• The growth series for the affine Weyl group E_7.at n=11A266785
• Numbers k > 0 such that either 3*k+4, k-2, k+2, n+k or 3*k+5, k-1, k+1, k+5 are all primes.at n=47A290130
• a(n) = n^4 + 4*n^2 + 3.at n=12A304726
• Expansion of Product_{k=1..10} (1+x^(2*k-1))/(1-x^(2*k)).at n=52A316722
• Odd numbers k such that sigma(k^2) > 2*k^2 and A003415(sigma(k^2)) < k^2.at n=44A347891
• Number of chordless cycles in the n X n rook complement graph.at n=6A361185
• G.f. A(x) satisfies A(x) = 1 / ((1 - x) * (1 - 2 * x * (1 + x + x^2 + x^3) * A(x^4))).at n=9A390658