A275279 Least k such that d(k*n) = d(k*(n+1)), or 0 if no such k exists (d = A000005).

0, 1, 2, 2, 12, 12, 4, 12, 2, 20, 72, 72, 28, 1, 6, 8, 108, 108, 160, 2, 1, 44, 288, 12, 2, 1, 2, 224, 10800, 10800, 16, 36, 1, 1, 6, 864, 76, 1, 4, 800, 21168, 21168, 352, 1, 3, 92, 1152, 24, 10, 4, 2, 416, 648, 9, 4, 4, 1, 116, 259200, 259200, 124

Offset

1,3

Links

Table of n, a(n) for n=1..61.

Example

a(4) = 2 because A000005(2*4) = A000005(2*5).

Prog

(PARI) a(n) = if(n==1, 0, {my(k = 1); while (numdiv(k*n) != numdiv(k*(n+1)), k++); k; })

Crossrefs

Cf. A000005.

Sequence in context: A327874 A190295 A228154 * A109767 A339297 A196061

Adjacent sequences: A275276 A275277 A275278 * A275280 A275281 A275282

Keyword

nonn

Author

Altug Alkan, Jul 28 2016

Status

approved