68400

Appears in sequences

• Iterated procedure 'composite k added to sum of its prime factors reaches a prime' yields 1 skipped prime.at n=29A050768
• Numbers containing squares of Pythagorean triples in their divisor set.at n=18A096472
• Numbers n such that 8*10^n-7 is prime.at n=23A099190
• Number of 8-step left-handed knight's tours (moves only out two, left one) on an n X n board summed over all starting positions.at n=12A187178
• Numbers with prime factorization pq^2r^2s^4.at n=7A190319
• Triangle of coefficients of a sequence of binomial type polynomials.at n=16A195205
• Numbers which divide the concatenation, in ascending order, of their anti-divisors.at n=32A249764
• Numbers n such that 2*n and n^3 have the same digit sum.at n=20A266315
• Triangle T(n,t) by rows: The number of rooted forests with n 3-colored nodes and t rooted trees.at n=40A271879
• First differences of A275315.at n=25A275066
• First differences of A275316.at n=25A275472
• Number of 2 X 2 matrices with entries in {0,1,...,n} and even trace with no entries repeated.at n=20A280056
• a(n) = sigma(sigma(p(n))) = sum of the divisors of the sum of the divisors of number of partitions of n.at n=35A280101
• Expansion of 1/(1 - Sum_{k>=1} lambda(k)*x^k), where lambda() is the Liouville function (A008836).at n=40A307076
• Integers i such that the equation A088387(i) = p has N > 1 solutions in the interval prevprime(i)..nextprime(i).at n=38A308617
• Integers k such that the equation A034699(k)=x has more than one solution in the range [prevprime(k), nextprime(k)].at n=4A308752
• Numbers k such that A348271(k) > 2*k.at n=32A348521
• Numbers that are both exponential and nonexponential abundant numbers.at n=23A348627
• Coreful triperfect numbers: numbers k such that csigma(k) = 3*k, where csigma(k) is the sum of the coreful divisors of k (A057723).at n=6A364990
• Exponential abundant numbers that are not exponential unitary abundant.at n=9A391085