A295220 a(n) = Sum_{i=1..floor(n/2)} floor((n+i)/i) - floor((n-i-1)/i).

0, 3, 3, 6, 5, 9, 7, 11, 10, 13, 11, 17, 13, 17, 17, 20, 17, 23, 19, 25, 23, 25, 23, 31, 26, 29, 29, 33, 29, 37, 31, 37, 35, 37, 37, 44, 37, 41, 41, 47, 41, 49, 43, 49, 49, 49, 47, 57, 50, 55, 53, 57, 53, 61, 57, 63, 59, 61, 59, 71, 61, 65, 67, 70, 67, 73

Offset

1,2

Comments

It appears that the odd prime numbers are fixed points of the sequence.

Links

Table of n, a(n) for n=1..66.

Maple

A295220:=n->add(floor((n+i)/i)-floor((n-i-1)/i), i=1..floor(n/2)): seq(A295220(n), n=1..120); # Wesley Ivan Hurt, Nov 29 2017

Mathematica

Table[Sum[Floor[(n + i)/i] - Floor[(n - i - 1)/i], {i, Floor[n/2]}], {n, 60}]

Crossrefs

Cf. A000040.

Sequence in context: A071047 A265008 A165606 * A280167 A257143 A080512

Adjacent sequences: A295217 A295218 A295219 * A295221 A295222 A295223

Keyword

nonn,easy

Author

Wesley Ivan Hurt, Nov 17 2017

Status

approved