27930

Appears in sequences

• Expansion of (1-x)^(-3) * (1-x^2)^(-2).at n=37A002624
• a(n) = n*(n+1)*(n+2)^2/6.at n=19A004320
• a(n) = n^3 + n^2 + n.at n=30A027444
• Composite numbers k such that the difference between the odd and even aliquot parts of k divides k.at n=27A066193
• Numbers n such that n*sigma(n) is a perfect square.at n=15A069070
• Expansion of (1 - 5*x - 2*x^2) / ((1 - x)*(1 + 2*x)*(1 - 6*x)).at n=7A091054
• a(n) = Sum_{k=1..A124259(n)} n^k.at n=29A124260
• Row squared sums of triangle of Lucas polynomials (A034807) for n>0: Sum_{k=0..floor(n/2)} A034807(n,k)^2, with a(0)=1.at n=12A132461
• 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, 1), (-1, 1, 0), (0, 1, -1), (0, 1, 0), (1, 0, 1)}.at n=8A150280
• Half the number of length n integer sequences with sum zero and sum of squares 8712.at n=3A157598
• Triangle read by rows: T(n,k) (n >= 0, 1 <= k <= n+1) are the signed Hultman numbers.at n=51A189507
• Numbers k with equal remainders of (product of divisors of k) mod (sum of divisors of k) and (product of proper divisors of k) mod (sum of proper divisors of k).at n=41A192035
• Places n such that the two remainders A187680(n) and A191906(n) are both zero.at n=16A192853
• Number of n X n binary arrays with every 1 immediately preceded by 0 0 to the left or above.at n=4A203102
• Number of n X 5 binary arrays with every 1 immediately preceded by 0 0 to the left or above.at n=4A203105
• T(n,k)=Number of nXk binary arrays with every 1 immediately preceded by 0 0 to the left or above.at n=40A203108
• a(n+2) = (2*n+1)^2*a(n+1) + (2*n+1)*(2*n-1)*a(n) with a(1)=1 and a(2)=2.at n=4A218768
• Numbers m such that the GCD of the x's that satisfy sigma(x) = m is 4.at n=30A241649
• Partial sums of A253088.at n=35A255048
• Positive integers n such that n=p+q for some primes p,q with pi(p)*pi(q) = sigma(n).at n=27A273286