27347

Appears in sequences

• Cubic star numbers: a(n) = n^3 + 4*Sum_{i=0..n-1} i^2.at n=23A051673
• Numbers n such that phi(n + phi(n)) = sigma(n).at n=19A074874
• Number of digits in the decimal expansion of the n-th Cullen prime.at n=9A137716
• Numbers n such that phi(n)=2*phi(n-1).at n=25A171271
• Numerator of H(n+4) - H(n), where H(n) = Sum_{k=1..n} 1/k.at n=32A189642
• a(n) = A205110(n)/n.at n=57A205111
• Maximal non-semiprime number which is a "preprime" of the n-th kind (defined in comment in A247395).at n=29A247834
• Least positive integer k such that prime(prime(k)), prime(prime(k*n)), prime(p) and prime(q) form a 4-term arithmetic progression for some pair of primes p and q.at n=21A261462
• Denominator of Product_{j=1..n-1} ((3*j+1)/(3*j+2)).at n=13A271920
• Denominator of n*Product_{j=1..n-1} ((3*j + 1)/(3*j + 2)).at n=13A271922
• Composite numbers k = concat(MSD(k),x) such that the sum of the aliquot parts of k is equal to the sum of the aliquot parts of x.at n=7A293479
• Least number k such that the determinant of the circulant matrix formed by its decimal digits is equal to k/n.at n=28A323485
• Partial sums of A334136.at n=36A332264
• Numbers that are the sum of eight fourth powers in exactly ten ways.at n=25A345842
• Deficiency of prime-shifted squares: a(n) = 2*A003961(n^2) - sigma(A003961(n^2)), where A003961 is fully multiplicative function with a(prime(i)) = prime(i+1).at n=53A378231