OFFSET
1,2
COMMENTS
If a(n) is an odd squarefree number with no gaps in its prime >= A065091(1) factors, b(n) is an odd squarefree number with no gaps in its prime >= A065091(2) factors, and c(n) is an odd squarefree number with no gaps in its prime >= A065091(3) factors, ..., then a(n) >= b(n) >= c(n) >= ... >= A056911(n).
EXAMPLE
MATHEMATICA
{1}~Join~Select[Range[3, 275, 2], And[SquareFreeQ@ #, MemberQ[{{}, {1}}, Union@ Differences@ PrimePi@ FactorInteger[#][[All, 1]]]] &] (* Michael De Vlieger, Nov 15 2017 *)
PROG
(PARI) isok(n) = {if ((n % 2) && issquarefree(n), f = factor(n); v = vector(#f~, k, primepi(f[k, 1])); for (k=2, #v, if (v[k] - v[k-1] != 1, return (0))); return (1); ); return (0); } \\ Michel Marcus, Nov 08 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Juri-Stepan Gerasimov, Nov 06 2017
EXTENSIONS
a(57) corrected by Rémy Sigrist, Nov 18 2017
STATUS
approved