20909

Appears in sequences

• Numbers k such that 3*2^k + 1 is prime.at n=24A002253
• Numbers whose base-12 representation has exactly 5 runs.at n=15A043654
• a(n) = Smallest nontrivial number k > 9 such that |first (leftmost) decimal digit of k - second digit + third digit - fourth digit ...| = n.at n=20A060982
• Smallest number m such that first digit - second digit + third digit - fourth digit ... (of m) = n.at n=20A061479
• a(n) = Smallest nontrivial number k > 9 such that first (leftmost) digit - second digit + third digit - fourth digit ... of k = n.at n=20A061882
• Minimum number k for which the digital sum of k*n is 2*n.at n=22A147822
• Positions of partition numbers in the EKG sequence.at n=36A159032
• Number of 9's in the last section of the set of partitions of n.at n=54A206559
• Numbers k such that 3*2^k + 1 is a prime factor of a generalized Fermat number 5^(2^m) + 1 for some m.at n=11A268658
• Numbers n such that 3*2^n + 1 is a prime factor of a generalized Fermat number 12^(2^m) + 1 for some m.at n=7A268660
• Numbers k such that (28*10^k + 131)/3 is prime.at n=23A282815
• Generalized Lucas-Carmichael numbers for D=9697.at n=41A290560
• Composite numbers k coprime to 8 such that k divides Pell(k - Kronecker(8,k)), Pell = A000129.at n=38A327651
• Position of the first occurrence of an element in the continued fraction of zeta(n) which is larger than the second element.at n=14A343244
• Positive integers k such that (k+1)^4 has a divisor congruent to -1 modulo k.at n=42A350916
• a(0) = 9, a(1) = 9, and a(n) = 3*a(n-1) - a(n-2) - 4 for n >= 2.at n=10A350919