OFFSET
1,1
COMMENTS
Composites not in A272601.
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
MATHEMATICA
pdkQ[n_]:=Module[{p=FactorInteger[n-1][[;; , 1]]-1}, AllTrue[(n-1)/p, IntegerQ]]; Select[Range[ 1550], CompositeQ[#]&&pdkQ[#]&] (* Harvey P. Dale, Feb 26 2024 *)
PROG
(PARI) forcomposite(n=4, 10^4, my(q=1, f=factor(n-1)[, 1]); for(j=1, #f, if((n-1)%(f[j]-1), q=0; break)); if(q, print1(n, ", ") ) );
(PARI) is(n)=my(f=factor(n-1)[, 1]); for(i=1, #f, if((n-1)%(f[i]-1), return(0))); !isprime(n) && n>1 \\ Charles R Greathouse IV, May 16 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Joerg Arndt, May 16 2016
STATUS
approved