123121

Properties

Appears in sequences

• Primes which are the reverse concatenation of two consecutive odd numbers.at n=16A104332
• Primes with digital product = 12.at n=30A107697
• a(n) = n base 5, under morphism f(1) = 121, f(2) = 123, f(3) = 141, f(4) = 142, or 0 if n base 5 has a zero.at n=10A137850
• Each of the numbers describes the previous number, and is described by the next number.at n=5A160265
• Numbers k such that k^p-p is prime, where p is product of the digits of k.at n=38A178328
• G.f.: Product_{k>=1} 1/(1-x^k)^(2*k-1).at n=17A253289
• Primes that can be generated by the concatenation in base 8, in ascending order, of two consecutive integers read in base 10.at n=37A287310
• Numbers k such that k*(k+1) divides tribonacci(k) (A000073(k)).at n=28A299156
• Indices of tetrahedral numbers that are Fermat pseudoprimes to base 2.at n=7A321866
• To get a(n), replace 0's in the binary expansion of n with (-1) and interpret the result in base n.at n=19A360096
• Lexicographically earliest sequence of prime numbers whose partial products, starting from the second, are all Fermat pseudoprimes to base 2 (A001567).at n=12A374028
• Lexicographically earliest strictly increasing sequence of prime numbers whose partial products, starting from the second, are all Fermat pseudoprimes to base 2 (A001567).at n=8A374029
• Prime numbersat n=11574