36208

Appears in sequences

• First occurrence of n consecutive numbers that take same number of steps to reach 1 in 3x+1 problem.at n=15A000546
• Numbers d*p where d is a perfect number and p<d a prime not dividing d.at n=27A165772
• The Wiener index of the graph \|/_\/_\/_..._\/_\|/ having n nodes on the horizontal path.at n=25A180571
• Number of trapezoids, distinct up to congruence, on an n X n grid (or geoboard).at n=15A181945
• a(n) = n*(n+1)*(7*n+2)/6.at n=31A255211
• Expansion of phi(x)^2 / phi(-x^2) in powers of x where phi() is a Ramanujan theta function.at n=36A260314
• Number of maximal subsets of {1..n} such that every orderless pair of distinct elements has a different sum.at n=27A325878
• Triangle read by rows: numerators of the almost-Riordan array ( 3*(7 - 4*x + sqrt(1 - 8*x))/(24 - 48*x + 16*x^2 + (3*x - 3)*(1 - 4*x - sqrt(1 - 8*x))) | 24/(24 - 48*x + 16*x^2 + (3*x - 3)*(1 - 4*x - sqrt(1 - 8*x))), (1 - 4*x - sqrt(1 - 8*x))/(8*x) ).at n=29A389706
• Numbers k with the property that k is the next lexicographically earliest number that cannot be expressed as a linear sum of the squares of preceding terms of the sequence with coefficients of 0, +1 or -1, with a(1)=1.at n=14A390487