65918161

Appears in sequences

• a(n)-th triangular number is a square: a(n+1) = 6*a(n) - a(n-1) + 2, with a(0) = 0, a(1) = 1.at n=11A001108
• Squares of NSW numbers (A002315): x^2 such that x^2 - 2y^2 = -1 for some y.at n=5A008843
• Expansion of 1/((1 - x)*(1 - 2*x - x^2)).at n=20A048739
• Repeatedly multiply (1,0,0) by ([1,2,2],[2,1,2],[2,2,3]); sequence gives leading entry.at n=11A090390
• Expansion of g.f. x/(1 - x - 3*x^2 - x^3).at n=22A097076
• a(n) = 2*a(n-1) + 2*a(n-3) + a(n-4), a(0) = 1, a(1) = 4, a(2) = 9, a(3) = 20.at n=20A111587
• Consider all Pythagorean triples (X,X+1,Z) ordered by increasing Z; sequence gives Z-(X+1) values.at n=10A115598
• Numbers k such that the distance between the k-th triangular number and the nearest square is at most 1.at n=40A229083
• Numbers k such that k and k+1 are both antiharmonic numbers (A020487).at n=18A335389