19199

Appears in sequences

• Pisot sequence E(3,13): a(n) = floor(a(n-1)^2/a(n-2) + 1/2).at n=6A010903
• Pisot sequence T(3,13), a(n) = floor( a(n-1)^2/a(n-2) ).at n=6A010920
• Sum of n plus its prime factors associated with A020700.at n=25A020905
• Denominators of continued fraction convergents to sqrt(761).at n=11A042467
• a(n) = 48*n^2 - 1.at n=20A065532
• Expansion of (1-x)^2/(1-5*x+3*x^2).at n=7A095934
• Difference between squares of legs of primitive Pythagorean triangles, sorted (with multiplicity).at n=34A127923
• a(n) = 12*n^2 - 1.at n=40A158463
• Triangle T(n, k) = A172452(n) - A172452(k) - A172452(n-k), read by rows.at n=56A172970
• Triangle T(n, k) = A172452(n) - A172452(k) - A172452(n-k), read by rows.at n=64A172970
• Riordan array (s(x),x*S(x)) where s(x) is the g.f. of the little Schroeder numbers A001003, and S(x) is the g.f. of the large Schroeder numbers A006318.at n=60A186826
• Numbers for which the root mean square of nontrivial divisors is an integer and which are not a square of prime numbers.at n=34A247137
• a(n) gives the odd leg of the second of the two Pythagorean triangles with hypotenuse A080109(n) = A002144(n)^2. This is the larger of the two possible odd legs.at n=19A253804
• Numbers n such that the sum of the digits of the numbers from 1 to n divides the sum of the numbers from 1 to n.at n=23A272360
• Numbers using only digits 1 and 9.at n=41A284294
• Numbers k such that the sum of decimal digits of k is the sum of primes dividing k+1 (with repetition).at n=25A339805
• a(n)^2 is the end of the first occurrence of n consecutive perfect powers, all of which are squares with exponents equal to 2 (A111245).at n=40A340664
• Smallest initial value for shortcut form of the Collatz function (3x+1)/2 sequence that begins with exactly n-1 increases and decreases once before the last increment.at n=6A383046