81919

Properties

Appears in sequences

• a(n) = 2*a(n-2) + 1.at n=28A010737
• Primes whose consecutive digits differ by 7 or 8.at n=18A048419
• Primes of form 5*2^n-1.at n=5A050522
• Start with n, apply k->2k+1 until reach new record prime; sequence gives record primes.at n=9A051919
• a(n) = 5*2^(n-1) - 1, n>0, with a(0)=1.at n=15A052549
• a(n) = T(n,1), array T as in A054134.at n=15A054135
• Primes of the form 2^r*5^s - 1.at n=20A077313
• Let t(x) be the highest power of 2 which divides x+1. Then a(1)=3; a(n) is the least prime p for which t(p) > t(a(n-1)).at n=9A084924
• a(0) = 2; for n>=1, a(n) = smallest prime p such that p+1 is divisible by an n-th power > 1.at n=14A087522
• Smallest prime with exactly n consecutive ones in the longest run of ones in its binary expansion.at n=13A090593
• Smallest prime of the form k*2^n - 1, for k >= 2.at n=14A127581
• a(n) = the smallest prime number of the form k*2^n - 1, for k >= 1.at n=14A127582
• Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, -1), (-1, -1, 1), (-1, 0, 1), (0, -1, 1), (1, 1, 0)}.at n=10A149143
• a(n) = 5*2^n - 1.at n=14A153894
• a(n) = 5*4^n - 1.at n=7A156760
• a(n) = 80*n^2 - 1.at n=31A158774
• Primes p such that 2*p^4+-9 are also prime.at n=35A174365
• Primes of the form 5n^2 - 1.at n=32A201783
• Least prime p such that p+1 is divisible by 2^n and not by 2^(n+1).at n=14A201914
• Primes of the form 4^k + 4^m - 1, where k and m are positive integers.at n=20A234310