19201

Appears in sequences

• Deceptive nonprimes: composite numbers k that divide the repunit R_{k-1}.at n=28A000864
• Number of steps to compute n-th prime in PRIMEGAME (fast version).at n=8A007546
• Pseudoprimes to base 15.at n=28A020143
• Strong pseudoprimes to base 10.at n=9A020236
• Strong pseudoprimes to base 100.at n=28A020326
• a(n) = n*(n^3 - 1)/2.at n=12A027482
• Numbers of the form k*(k^3 +- 1)/2.at n=26A057590
• Numbers k such that the digits of k^2 are exactly the same (albeit in different order) as the digits of (k+1)^2.at n=5A072841
• Nonprimes k such that k divides 3^(k-1) - 2^(k-1).at n=35A073631
• a(n) = A077741(n)/n.at n=48A077742
• Number of permutations of length n which avoid the patterns 1234, 2431, 4132.at n=10A116835
• a(n) = 12*n^2 + 1.at n=40A158480
• a(n) = 48*n^2 + 1.at n=20A158638
• a(n) = (2*n^3 + 5*n^2 - 5*n)/2.at n=25A162265
• Totally multiplicative sequence with a(p) = a(p-1) + 6 for prime p.at n=45A166703
• Numbers k such that 3^(k-1) == 2^(k-1) !== 1 (mod k).at n=24A285300
• Coefficients in asymptotic expansion of sequence A096161 and A161779.at n=9A293266
• Lexicographically earliest sequence of distinct positive integers such that a(n), a(n+1) and the product a(n)*a(n+1) have in common the substring n.at n=19A333933
• Odd composite integers m such that A006497(m) == 3 (mod m).at n=27A335669
• The leftmost digit L of a(n) jumps over L+1 digits to the left and is duplicated there; the rightmost digit R of a(n) jumps over R digits to the right and is duplicated there. Lexicographically earliest sequence of distinct positive integers with this property and a(1) = 11.at n=42A336036