19669

Appears in sequences

• a(n) = n*(n^2 + 1)/2.at n=34A006003
• Pseudoprimes to base 21.at n=35A020149
• Strong pseudoprimes to base 21.at n=9A020247
• Strong pseudoprimes to base 47.at n=14A020273
• Strong pseudoprimes to base 72.at n=13A020298
• Strong pseudoprimes to base 98.at n=21A020324
• a(n) = (2*n + 1)*(5*n + 1).at n=44A033571
• Number of primes of the form 8k+7 less than 10^n.at n=5A091129
• Binomial transform of the "1,2,3,..." triangle.at n=57A125027
• Expansion of -x*(x^5+11*x^4+x^3+x^2+21*x-4) / ((x^2+x-1)*(3*x^4+7*x-1)).at n=5A134823
• Positions of hexagonal pyramidal numbers in the EKG sequence.at n=30A144080
• Numbers n such that d(n + d(n)) = d(n), where d(n) is the sum of the distinct primes dividing n.at n=25A175760
• Numbers k such that 2^(2k-1) == 2 (mod 2k) and such that 2^(k-1) != 1 (mod k).at n=33A176033
• Partial sums of A079062.at n=37A177455
• Number of (n+1) X (n+1) -3..3 symmetric matrices with every 2 X 2 subblock having sum zero and one, three or four distinct values.at n=10A211327
• Row sums of the triangular array A246696.at n=33A246697
• 37-gonal numbers: a(n) = n*(35*n-33)/2.at n=34A282852
• a(n) = (n - 1)*(4*n^2 - 8*n + 5).at n=17A317297
• Odd composite integers m such that A014448(m) == 4 (mod m).at n=34A335670
• Odd composite integers m such that U(m)^2 == 1 (mod m) and V(m) == 4 (mod m), where U(m) and V(m) are the m-th generalized Lucas and Pell-Lucas numbers of parameters a=4 and b=-1, respectively.at n=27A337627