99990001

Properties

Appears in sequences

• Irregular table read by rows: row n lists prime factors of 10^n + 1, with multiplicity.at n=31A001271
• Largest prime factor of the "repunit" number 11...1 (cf. A002275).at n=22A003020
• Largest prime factor of 10^n + 1.at n=12A003021
• Largest prime factor of 10^n - 1.at n=23A005422
• Duodecimal primes: p = (x^12 + y^12 )/(x^4 + y^4 ).at n=15A006687
• Smallest primitive factor of 10^n - 1. Also smallest prime p such that 1/p has repeating decimal expansion of period n.at n=23A007138
• Primes with unique period length (the periods are given in A007498).at n=10A007615
• Cyclotomic polynomials at x=10.at n=23A019328
• Divisors of 10^12 + 1.at n=4A027898
• Prime 3 followed by unique period primes (the period r of 1/p is not shared with any other prime) of the form A019328(r)/gcd(A019328(r),r) in order (periods r are given in A051627).at n=8A040017
• Numbers m such that m^2 is a concatenation of two consecutive decreasing numbers.at n=6A054216
• a(n) = n^8 - n^4 + 1.at n=10A060893
• Greatest prime number p(n) with decimal fraction period of length n.at n=23A061075
• Largest prime factor of 10^(6*n) + 1.at n=1A072848
• a(n) = A083147(n+1)/A083147(n).at n=14A083148
• a(n) = A083153(n+1)/A083153(n).at n=12A083154
• a(n) = A083153(n+1)/A083153(n).at n=15A083154
• Primes arising as the successive difference of terms of A088052. a(n) = A088052(n+1)-A088052(n).at n=34A088053
• a(n) = A082780(n+1)/A082780(n).at n=6A088775
• a(n)=A082781(n+1)/A082781(n).at n=6A088776