21900

Appears in sequences

• Numbers having four 3's in base 9.at n=6A043468
• Triangle read by rows, T(n, k) = Sum_{i=0..n} L'(n, n-i) * binomial(i, k), for k = 0..n-1.at n=17A059374
• 55 'Reverse and Add' steps are needed to reach a palindrome.at n=3A065322
• a(n) is the floor of the average of the 1st moment of all previous entries.at n=18A092483
• Numbers that have exactly six prime factors counted with multiplicity (A046306) whose digit reversal is different and also has 6 prime factors (with multiplicity).at n=33A109026
• a(n) = 16*n^2 - 4.at n=36A158443
• Number of strings of numbers x(i=1..n) in 0..7 with sum i^3*x(i)^2 equal to n^3*49.at n=9A184301
• Trisection of A107926: The least number k such that there are primes p and q with p - q = 6*n+2, p + q = k, and p the least such prime >= k/2.at n=32A234955
• Number of partially ordered partitions of n into parts less than or equal to 3, in which the order of adjacent 2's and 3's is unimportant.at n=18A254685
• Sum of numbers in the n-th antidiagonal of the reciprocity array of 2.at n=44A259580
• Exponential (2,3)-perfect numbers: numbers m such that esigma(esigma(m)) = 3m, where esigma(m) is the sum of exponential divisors of m (A051377).at n=19A328132