A144771 For n >= 1 terms of A000142 could be expressed as the product of two nonzero integral factors, which have the smallest difference between them (so this is closest pair of integral factors around the square root value of A000142(n) ). The terms of this sequence are the larger factors from the above described pair.

1, 2, 3, 6, 12, 36, 84, 210

Offset

1,2

Comments

1! = 1*1; 1 >=sqrt(1!), so a(1)= 1 2! = 2*1; 2 > sqrt(2!), so a(2)= 2 3! = 3*2; 3 > sqrt(3!), so a(3)= 3 4! = 6*4; 6 > sqrt(4!), so a(4)= 6 5! = 12*10; 12> sqrt(5!), so a(5)= 12 6! = 36*20; 36> sqrt(6!), so a(6)= 36 7! = 84*60; 84> sqrt(7!), so a(7)= 84 8! = 210*192; 210> sqrt(8!), so a(8)= 210

Links

Table of n, a(n) for n=1..8.

Crossrefs

Cf. A000142

Sequence in context: A243299 A096746 A102970 * A187013 A295324 A054049

Adjacent sequences: A144768 A144769 A144770 * A144772 A144773 A144774

Keyword

nonn

Author

Alexander R. Povolotsky, Sep 20 2008

Status

approved