51688

Appears in sequences

• a(n) = floor(n(n-1)(n-2)(n-3)/19).at n=33A011929
• a(n) = f(n,n+2) where f is given in A034261.at n=7A034269
• Numbers k such that sigma(k) = bigomega(k) * phi(k).at n=18A067238
• Numbers n such that sigma(n) = 6*phi(n).at n=13A104900
• Number of nondecreasing integer sequences of length 9 with sum zero and sum of absolute values 2n.at n=20A158143
• Number of n X n 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 0,2,1,0,0 for x=0,1,2,3,4.at n=5A198178
• Number of nX6 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 0,2,1,0,0 for x=0,1,2,3,4.at n=5A198183
• T(n,k)=Number of nXk 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 0,2,1,0,0 for x=0,1,2,3,4.at n=60A198185
• Number of ways of arranging n chords on a circle (handshakes between 2n people across a table) with exactly 3 simple intersections.at n=8A232224
• Number T(n,k) of modified skew Dyck paths of semilength n with exactly k anti-down steps; triangle T(n,k), n>=0, 0<=k<=n-floor((1+sqrt(max(0,8n-7)))/2), read by rows.at n=39A274404
• Larger of amicable pair m < n defined by t(n) = m and t(m) = n where t(n) = psi(n) - n and psi(n) = A001615(n) is the Dedekind psi function.at n=22A323330
• Numbers that are the sum of five fifth powers in two or more ways.at n=3A342685
• Numbers that are the sum of five fifth powers in exactly two ways.at n=3A342686
• Numbers that are the sum of four third powers in nine or more ways.at n=12A345146
• Numbers that are the sum of four third powers in eight or more ways.at n=36A345152
• Numbers that are the sum of four third powers in exactly nine ways.at n=6A345154