A253975 a(n) is the smallest number k representable as x*y+x+y, where x>=y>1, in exactly n ways, or -1 if no such k exists.

8, 23, 35, 59, 191, 119, 179, 239, 575, 359, 1295, 899, 719, 839, 9215, 1259, 17324, 1679, 2879, 15359, 3599, 2519, 6479, 61439, 6299, 6719, 280664, 5039, 155924, 7559, 46079, 983039, 25919, 10079, 225224, 32399, 184319, 15119, 44099, 20159, 1403324, 107519, 25199

Offset

1,1

Comments

a(45) = 8303765624.

Conjecture: no term is -1.

Links

Table of n, a(n) for n=1..43.

Example

a(1) = 8 = 2*2+2+2.
a(2) = 23 = 5*3+5+3 = 7*2+7+2.
a(3) = 35 = 11*2+11+2 = 8*3+8+3 = 5*5+5+5.

Crossrefs

Sequence in context: A283848 A341770 A287167 * A003342 A345833 A164284

Adjacent sequences: A253972 A253973 A253974 * A253976 A253977 A253978

Keyword

nonn

Author

Alex Ratushnyak, Jan 24 2015

Status

approved