A108843
Palindromic primes in which all internal digits are 6.
Original entry on oeis.org
16661, 76667, 7666667, 1666666666661, 16666666666666661, 1666666666666666661, 1666666666666666666666666666666666661, 16666666666666666666666666666666666666666666666666661
Offset: 1
-
nn=80;With[{o=Table[FromDigits[Join[PadRight[{1},n,6],{1}]],{n,3,nn}], s= Table[ FromDigits[Join[PadRight[{7},n,6],{7}]],{n,3,nn}]}, Select[ Sort[ Join[o,s]],PrimeQ]] (* Harvey P. Dale, May 26 2014 *)
-
n10np1(n,d) = { local(x,y,k); for(x=1,n, for(k=1,8, y=10^(x+1)*k+floor(10^x*d/9)*10+k; if(isprime(y),print1(y",")) ) ) }
-
from sympy import isprime
from itertools import count, islice
def agen(): yield from (t for i in count(1) for f in "17" if isprime(t:=int(f + "6"*i + f)))
print(list(islice(agen(), 10))) # Michael S. Branicky, Jan 27 2023
A108845
Palindromic primes in which all internal digits are 1.
Original entry on oeis.org
313, 919, 3111111111113, 311111111111113, 1111111111111111111, 11111111111111111111111, 3111111111111111111111111111113
Offset: 1
-
n10np1(n,d) = { local(x,y,k); for(x=1,n, for(k=1,9, y=10^(x+1)*k+floor(10^x*d/9)*10+k; if(isprime(y),print1(y",")) ) ) }
-
from sympy import isprime
from itertools import count, islice
def agen(): yield from (t for i in count(1) for f in "1379" if isprime(t:=int(f + "1"*i + f)))
print(list(islice(agen(), 10))) # Michael S. Branicky, Jan 27 2023
A108846
Palindromic primes in which all internal digits are 2.
Original entry on oeis.org
727, 929, 72227, 3222223, 9222229, 322222223, 722222227, 9222222222229, 72222222222222222222222222227, 72222222222222222222222222222222222222222222222222222222222222227
Offset: 1
-
Select[Flatten[Table[10 FromDigits[PadRight[{d},n,2]]+d,{d,{1,3,7,9}},{n,2,70}]],PrimeQ]//Sort (* Harvey P. Dale, Feb 05 2023 *)
-
n10np1(n,d) = { local(x,y,k); for(x=1,n, for(k=1,9, y=10^(x+1)*k+floor(10^x*d/9)*10+k; if(isprime(y),print1(y",")) ) ) }
-
from sympy import isprime
from itertools import count, islice
def agen(): yield from (t for i in count(1) for f in "1379" if isprime(t:=int(f + "2"*i + f)))
print(list(islice(agen(), 10))) # Michael S. Branicky, Jan 27 2023
A108847
Palindromic primes in which all internal digits are 8.
Original entry on oeis.org
181, 383, 787, 78887, 9888889, 188888881, 3888888888883, 188888888888881, 3888888888888888888888888888883, 18888888888888888888888888888888888888881
Offset: 1
-
n10np1(n,d) = { local(x,y,k); for(x=1,n, for(k=1,9, y=10^(x+1)*k+floor(10^x*d/9)*10+k; if(isprime(y),print1(y",")) ) ) }
-
from sympy import isprime
from itertools import count, islice
def agen(): yield from (t for i in count(1) for f in "1379" if isprime(t:=int(f + "8"*i + f)))
print(list(islice(agen(), 10))) # Michael S. Branicky, Jan 27 2023
Showing 1-4 of 4 results.
Comments