21907

Appears in sequences

• Number of ferrites M_{10}Y_n that repeat after 6n+50 layers.at n=14A011964
• Numbers with sum of digits = 19, divisible by 19 and containing the string "19".at n=5A121669
• a(n) is the smallest positive integer x such that x^2 - n! is prime.at n=11A143931
• a(1)=3; for n > 1, a(n) = 1 + a(n-1) + gcd( a(n-1)*(a(n-1)+2), A073829(a(n-1)) ).at n=35A167053
• Number of binary arrays indicating the locations of trailing edge maxima of a random length-n 0..2 array extended with zeros and convolved with 1,3,3,1.at n=22A222021
• a(n) = n*(7*n^2-12*n+7)/2.at n=19A226451
• G.f.: 1/(1 - x - x^2 - x^3 + x^5 + x^6 + x^7).at n=19A227376
• Number of partitions p of n such that 2*(number of even numbers in p) > (number of odd numbers in p).at n=39A241655
• Composites whose prime factorization in base 12 is an anagram of the number in base 12.at n=9A260055
• Odd numbers k such that A064989(k) is in A340151.at n=30A340091
• a(0)=0; for n > 0, a(n) = 2*a(n-1) if n-1 is prime, a(n-1) + 1 otherwise.at n=43A354973
• Semiprimes of the form k^2 + 3.at n=31A360740
• Squarefree terms of A129802 whose prime factors are neither elite (A102742) nor anti-elite (A128852), where A129802 is the possible bases for Pepin's primality test for Fermat numbers.at n=7A372895