OFFSET
1,1
COMMENTS
Original definition: Pseudofactor sets of primes ending in 1: 7 greater than 3.
These pseudofactors, although not unique sets as their domains seem to overlap, form twelve subsets of primes based on the first digit set {1,3,7,9} when {2,5} are taken away from the prime set. This is one of the four {1}'s sets. There exist {3}'s, {7}'s and {9}'s sets of these same four types.
Primes ending in 1 are listed if Mod[floor(a[n]/7), 10]>3, where Mod is the binary "remainder" operator.
Primes == 31, 41, 51 or 61 (mod 70). - Robert Israel, Jun 14 2019
LINKS
Robert Israel, Table of n, a(n) for n = 1..10000
MAPLE
select(isprime, [seq(seq(70*i+j, j=[31, 41, 51, 61]), i=0..100)]); # Robert Israel, Jun 14 2019
MATHEMATICA
digits=4*200 a=Delete[Union[Table[If[Mod[Prime[n], 10]==1, Prime[n], 0], {n, 1, digits}]], 1] d2=Dimensions[a][[1]] a7g3=Delete[Union[Table[If[Mod[a[[n]]/7, 10]>3, a[[n]], 0], {n, 1, d2}]], 1]
pe1Q[n_]:=Mod[n, 10]==1&&Mod[Floor[n/7], 10]>3; Select[Prime[Range[ 300]], pe1Q] (* Harvey P. Dale, Mar 26 2012 *)
PROG
(PARI) forprime( p=1, 9999, p%10==1 & p\7%10>3 & print1(p", ")) \\ M. F. Hasler, Apr 06 2009
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Roger L. Bagula, Jan 06 2004
EXTENSIONS
Corrected and edited by M. F. Hasler, Apr 06 2009
STATUS
approved