26405

Appears in sequences

• Consider a 2-D cellular automaton generated by the Schrandt-Ulam rule of A170896, but confined to a semi-infinite strip of width n, starting with one ON cell at the top left corner; a(n) is the period of the resulting structure.at n=51A006447
• Shifts 3 places left under exponentiation.at n=11A007548
• a(n+1) = a(n) converted to base 8 from base 7 (written in base 10).at n=36A023388
• Smallest k>1 such that k(p-1)-1 is divisible by p^2, p=n-th prime.at n=37A039914
• Becomes prime or 4 after exactly 9 iterations of f(x) = sum of prime factors of x.at n=19A048131
• Nonzero numerators in asymptotic expansion of the Riemann-Seigel Z-function.at n=28A050276
• p^2-p-1 that is not prime, where p is prime.at n=20A119609
• Numbers n such that phi(n)=2*phi(n-1).at n=24A171271
• Numbers k such that C(k+2,2) divides 2^(k+1) - 1.at n=21A246636
• a(n) = Sum_{m=0..floor((n-1)/2)} prime((n-m)(n-m-1)/2+m+1).at n=29A249490
• a(n) = p^2 - p - 1 where p = prime(n), the n-th prime.at n=37A306190