A046407 -id:A046407 - cp's OEIS frontend

A046391 Odd numbers with exactly 5 distinct prime factors.

15015, 19635, 21945, 23205, 25935, 26565, 31395, 33495, 33915, 35805, 36465, 39585, 40755, 41055, 42315, 42735, 45885, 47355, 49335, 49665, 50505, 51051, 51765, 53295, 54285, 55335, 55965, 57057, 57855, 58695, 61215, 61845, 62205

Offset: 1

Patrick De Geest, Jun 15 1998

nonn

			50505 = 3 * 5 * 7 * 13 * 37.

Karl-Heinz Hofmann, Table of n, a(n) for n = 1..10000 (first 1000 terms from T. D. Noe)

Cf. A046318, A046407.

Intersection of A051270 and A005408.

isA046391 := proc(n)
    type(n,'odd') and (A001221(n) = 5 ) ;
end proc:
for n from 1 do
    if isA046391(n) then
        print(n);
    end if;
end do: # R. J. Mathar, Nov 10 2014

f[n_]:=Last/@FactorInteger[n]=={1,1,1,1,1}&&FactorInteger[n][[1,1]]>2; lst={};Do[If[f[n],AppendTo[lst,n]],{n,9!}];lst (* Vladimir Joseph Stephan Orlovsky, Nov 23 2009 *)

from sympy import primefactors, factorint
print([n for n in range(1, 100000, 2) if len(primefactors(n)) == 5 and max(list(factorint(n).values())) < 2]) # Karl-Heinz Hofmann, Mar 01 2023

A046375 Odd numbers with exactly 5 palindromic prime factors (counted with multiplicity).

Original entry on oeis.org

243, 405, 567, 675, 891, 945, 1125, 1323, 1485, 1575, 1875, 2079, 2205, 2475, 2625, 3087, 3125, 3267, 3465, 3675, 4125, 4375, 4851, 5145, 5445, 5775, 6125, 6875, 7203, 7623, 8085, 8181, 8575, 9075, 9625, 10611, 11319, 11979, 12005, 12231, 12705

Offset: 1

Patrick De Geest, Jun 15 1998

Robert Israel, Table of n, a(n) for n = 1..10000

Cf. A046318, A046407.

rev:= proc(n) local L,d,i;
  L:= convert(n,base,10);
  d:= nops(L);
  add(L[i]*10^(d-i),i=1..d);
end proc:
PP:= NULL:
for d from 1 to 3 do
  for x from 10^(d-1) to 10^d-1 do
    y:= x*10^(d-1) + rev(floor(x/10));
    if isprime(y) then PP:= PP,y fi;
  od;
  if d = 1 then PP:= PP,11 fi;
od:
PP:= [PP][2..-1]:
npp:= nops(PP):
N:= PP[-1]*3^4:
Res:= NULL:
for i1 from 1 to npp do
     v1:= PP[i1];
     for i2 from 1 to i1 do
       v2:= v1*PP[i2];
       if v2*3^3 > N then break fi;
       for i3 from 1 to i2 do
         v3:= v2*PP[i3];
         if v3 * 3^2 > N then break fi;
         for i4 from 1 to i3 do
           v4:= v3*PP[i4];
           if v4* 3 > N then break fi;
           for i5 from 1 to i4 do
             v:= v4*PP[i5];
             if v > N then break fi;
             Res:= Res, v
od od od od od:
sort([Res]); # Robert Israel, Mar 15 2024

Offset corrected by Robert Israel, Mar 15 2024

cp's OEIS Frontend

A046391 Odd numbers with exactly 5 distinct prime factors.

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