20021

Properties

Appears in sequences

• a(n) = n^2 written in base 3.at n=13A001738
• n written in fractional base 4/2.at n=37A024630
• Primes having only {0, 1, 2} as digits.at n=15A036953
• Primes whose sum of digits is 5.at n=22A062341
• Smallest n-digit prime with all even digits except the least significant digit.at n=4A068691
• Primes with arithmetic mean of digits = 1 (sum of digits = number of digits).at n=12A069710
• Define C(n) by the recursion C(0) = 2*i where i^2 = -1, C(n+1) = 1/(1 + C(n)), then a(n) = 2*(-1)^n/Im(C(n)) where Im(z) denotes the imaginary part of the complex number z.at n=10A069959
• Duplicate of A069710.at n=12A073903
• Prime numbers such that first reversing digits and after squaring equals the result of first-squaring and after-reversing. Primes in A085305.at n=29A085306
• Primes p of the form k*(k + 1) - 1 such that p and p + 2 are twin primes.at n=19A088486
• Primes prime(k) such that (prime(k-1) + prime(k+1) + prime(k+2))/prime(k) = 3.at n=34A094933
• Primes of form n.0.n+1, where '.' represents concatenation. Or, primes of form 10^(k+1)*n + n + 1, where k is the number of digits in n.at n=2A096525
• Primes p whose period of reciprocal equals (p-1)/13.at n=4A098680
• Primes with maximal digit = 2.at n=12A106100
• Primes with at most n digits and a digit sum n in ascending order. 2,11; 3; 13,31,103,211,1021,2011,3001; 5,23,41,113,...at n=33A110741
• Prime values of integers written in factorial base, interpreted as in base 10.at n=38A121402
• Primes p that divide Fibonacci[(p-1)/7].at n=27A125253
• Primes congruent to 20 mod 59.at n=39A142747
• a(n) = A000043(n) written in base 4.at n=12A161322
• Primes of the form ((p+1)/2)^2+((p-1)/2), where p is prime.at n=26A163419