OFFSET
1,1
COMMENTS
Note that a(n) = 1 for n= 2, 4, 11, 31, 1028, ... (A059305). - Michel Marcus, Oct 01 2013
FORMULA
PROG
(PARI) a(n) = my(p = prime(n) + 1, v = p/(2^valuation(p, 2))) ; if (v == 1, 1, factor(v)[1, 1]); \\ Michel Marcus, Oct 01 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved