138240

Appears in sequences

• Number of invertible 2 X 2 matrices mod n.at n=29A000252
• Multiply successively by 1 (once), 2 (twice), 3 (thrice), etc.at n=11A010552
• Exponential generating function = (1+2*x)/(1-2*x)^3.at n=5A014479
• Triangle whose (i,j)-th entry is binomial(i,j)*4^(i-j)*6^j.at n=23A038236
• Triangle whose (i,j)-th entry is binomial(i,j)*6^(i-j)*4^j.at n=25A038258
• Triangle whose (i,j)-th entry is binomial(i,j)*6^(i-j)*8^j.at n=17A038262
• Triangle whose (i,j)-th entry is binomial(i,j)*8^(i-j)*6^j.at n=18A038284
• Sum of divisors of those numbers n such that n and n+1 have the same sum of divisors.at n=22A053215
• Sum of divisors of k such that k and k+1 have the same number and sum of divisors.at n=7A054005
• Numbers k such that, in the prime factorization of k, the product of exponents equals the product of prime factors.at n=21A054412
• a(n) = tau( sigma_n(n) ), where tau is the number of divisors of n.at n=41A064165
• Eighth column of triangle A067417.at n=4A067423
• Smallest k-almost prime between twin primes (for k >= 2).at n=12A068525
• 14-almost primes (generalization of semiprimes).at n=16A069275
• a(n) = [n/1][n/2][n/3] ...[n/n] / n^(tau(n)/2).at n=25A076891
• Denominators of coefficients of series expansion of a certain integral in the theory of charged particle beams.at n=4A077231
• a(1) = 3 then a(n) = smallest multiple of a(n-1) > a(n-1) such that a(n) - 1 is a prime.at n=10A084717
• a(n) = 2^n * Lucas(n) * (n-1)!.at n=5A097632
• Sum of the non-unitary divisors of A064115(n) (or of 1+A064115(n)).at n=10A103846
• Terms of A110142 at positions p(n)+1, where p(n) = A000041(n) is the number of partitions of n; a(n) = A110142(p(n)+1) for n>=1, with a(0) = 1.at n=14A110144