28157

Appears in sequences

• Number of prime powers p^k (k != 1) <= 10^n.at n=11A076048
• Duplicate of A076048.at n=11A077270
• Expansion of 1/(1 - x - x^3 + x^5).at n=49A123552
• a(n) = 78*n^2 - 1.at n=18A158771
• Irregular triangular array: row n gives numbers D, each being the discriminant of the minimal polynomial of a quadratic irrational represented by a continued fraction with period an n-tuple of 1s and 3s.at n=42A246921
• Irregular triangular array: every periodic simple continued fraction CF represents a quadratic irrational (c + f*sqrt(d))/b, where b,c,f,d are integers and d is squarefree. Row n of this array shows the distinct values of d as CF ranges through the periodic continued fractions having period an n-tuple of 1s and 3s.at n=42A246922