19968

Appears in sequences

• Fibonacci iteration starting with (1, a(n)) leads to a "nine digits anagram".at n=30A034587
• First element r of (-1)sigma sociable triple (r,s,t): s=(-1)sigma(r), t=(-1)sigma(s), r=(-1)sigma(t), where if x=Product p(i)^r(i), then (-1)sigma(x)=Product(-1+(Sum p(i)^s(i), s(i)=1 to r(i))).at n=21A049057
• Third element t of (-1)sigma sociable triple (r,s,t): s=(-1)sigma(r), t=(-1)sigma(s), r=(-1)sigma(t), where if x=Product p(i)^r(i), then (-1)sigma(x)=Product(-1+(Sum p(i)^s(i), s(i)=1 to r(i))).at n=5A049059
• McKay-Thompson series of class 24B for Monster.at n=29A058572
• Unicode codes for the Han digits.at n=1A061745
• a(n) = Product_{i=1..n} phi(i) * Sum_{i=1..n} 1/phi(i) where phi is the Euler totient function A000010(n).at n=8A067578
• 11-almost primes (generalization of semiprimes).at n=21A069272
• Number of permutations pi in S_n such that maj pi and maj pi^(-1) have opposite parity where maj is the major index. Equivalently, the number of pi such that maj pi and inv pi have opposite parity where inv is the inversion number.at n=7A113248
• Main diagonal of array A[k,n] = n-th sum of 3 consecutive k-gonal numbers, k>2.at n=23A130423
• 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, 1, -1)}.at n=9A148763
• Number of ways to place 3 nonattacking bishops on an n X n toroidal board.at n=7A177756
• a(n) = Product_{k>=1} floor(n^(1/k)).at n=77A190668
• Numbers k such that (number of prime factors of k counted with multiplicity) less (number of distinct prime factors of k) = 8.at n=30A195092
• McKay-Thompson series of class 24B for the Monster group with a(0) = 2.at n=29A212771
• G.f.: Sum_{n>=0} (4*n+3)^n * x^n / (1 + (4*n+3)*x)^n.at n=4A221161
• a(n) = sigma(2*n^3) - sigma(n^3).at n=19A225959
• Denominators of a sequence defined by a modified recurrence for the exponential of the von Mangoldt function.at n=24A277440
• Decimal representation of the x-axis, from the origin to the right edge, of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 355", based on the 5-celled von Neumann neighborhood.at n=14A281307
• Decimal representation of the diagonal from the origin to the corner of the n-th stage of growth of the two-dimensional cellular automaton defined by "Rule 358", based on the 5-celled von Neumann neighborhood.at n=16A287785
• Integers with precisely four partitions into sums of four squares of nonnegative numbers.at n=45A294282