27381

Appears in sequences

• Concatenations C1 and C2 and C3 are all prime (see the comment lines).at n=6A034818
• Numbers k such that lcm(1,2,3,...,k)/13 equals the denominator of the k-th harmonic number H(k).at n=7A112818
• Shorthand for A157035, the largest prime with 2^n digits.at n=11A157036
• a(n) = 20*n^2 + 1.at n=37A158493
• Semiprimes of the form 5*n^2 + 1.at n=25A212707
• Number of partitions of n such that the absolute value of the difference between the number of odd parts and the number of even parts is <=1.at n=48A239835
• a(1) = 1; for n > 1, a(n) = a(n-1) + A255411(a(n-1)).at n=5A265907
• Numbers n such that 7^n-6^(n-1) is prime.at n=18A273524
• Square array A(1,k) = A265907(k), A(n>1,k) = A(n-1, k+1) - A(n-1, k); successive differences of A265907 read by descending antidiagonals as A(1,1), A(1,2), A(2,1), A(1,3), A(2,2), A(3,1), ...at n=15A275960
• Transpose of array A275960.at n=20A275961