24887

Appears in sequences

• Numbers n such that 9*10^n + 5*R_n - 2 is prime, where R_n = 11...1 is the repunit (A002275) of length n.at n=7A103101
• Numbers k such that sigma(k) - phi(k) is a 4th power.at n=26A115918
• Number of permutations of length n which avoid the patterns 312, 1324, 3421; or avoid the patterns 312, 1324, 2341, etc.at n=28A116722
• Numbers k such that 58/111*(10^(3*k)-1)-1 is prime.at n=13A178321
• Smallest zeroless number x such that x^n has exactly n zero digits.at n=19A233821
• a(n) = number of regions in the configuration A290447(n).at n=29A290865