A137532 a(n) is the smallest positive integer k such that d(k) = d(k+n) = 2*n, where d(m) (A000005) is the number of positive divisors of m, or 0 if no such k exists.

2, 6, 172, 66, 15952, 84, 22592, 888, 2196, 3750, 459932661, 660, 86817796083, 185152, 143366096, 5304, 17685013528576, 3150, 1786574475624429, 1272510, 29059703104, 12872682, 4817557477673402368, 9576, 85608255863, 15744471040, 1179648, 124718750, 1765038427619364800823267

Offset

1,1

Links

Table of n, a(n) for n=1..29.

Prog

(PARI) lq080419b(n, a)=n*=2; until(0, numdiv(a++)==n || next; numdiv(a+n\2)==n && break); a
for(i=1, 99, print1(lq080419b(i)", "))

Crossrefs

Cf. A000005, A139416.

Sequence in context: A168649 A135937 A182523 * A072116 A203430 A298883

Adjacent sequences: A137529 A137530 A137531 * A137533 A137534 A137535

Keyword

nonn

Author

M. F. Hasler, Apr 19 2008

Extensions

a(11) from Jacques Tramu, Apr 20 2008

More terms from Jinyuan Wang, May 08 2021

Status

approved