A274677
Numbers k such that 7*10^k + 19 is prime.
Original entry on oeis.org
1, 2, 3, 4, 27, 32, 63, 69, 107, 145, 154, 173, 190, 271, 412, 1219, 1509, 2392, 4444, 5567, 7424, 32174, 51573
Offset: 1
3 is in this sequence because 7*10^3 + 19 = 7019 is prime.
5 is not in the sequence because 7*10^5 + 19 = 79*8861.
Initial terms and associated primes:
a(1) = 1: 89;
a(2) = 2: 719;
a(3) = 3: 7019;
a(4) = 4: 70019, etc.
Cf. similar sequences listed in
A274676.
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[n: n in [1..800] | IsPrime(7*10^n+19)];
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Select[Range[0, 3000], PrimeQ[7 10^# + 19] &]
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lista(nn) = for(n=1, nn, if(ispseudoprime(7*10^n+19), print1(n, ", "))); \\ Altug Alkan, Jul 05 2016
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from sympy import isprime
def afind(limit, startk=0):
sevenpow10 = 7*10**startk
for k in range(startk, limit+1):
if isprime(sevenpow10 + 19):
print(k, end=", ")
k += 1
sevenpow10 *= 10
afind(500) # Michael S. Branicky, Dec 31 2021
a(22)-a(23) from Kamada data by
Tyler Busby, Apr 14 2024
A274678
Numbers k such that 7*10^k + 27 is prime.
Original entry on oeis.org
1, 2, 3, 5, 7, 34, 38, 49, 51, 89, 91, 132, 227, 3662, 5019, 9729, 25437, 99944, 106553, 114577
Offset: 1
3 is in this sequence because 7*10^3 + 27 = 7027 is prime.
4 is not in the sequence because 7*10^4 + 27 = 70027 = 239 * 293.
Initial terms and associated primes:
a(1) = 1: 97;
a(2) = 2: 727;
a(3) = 3: 7027;
a(4) = 5: 700027, etc.
Cf. similar sequences listed in
A274676.
-
[n: n in [1..800] | IsPrime(7*10^n+27)];
-
Select[Range[0, 3000], PrimeQ[7 10^# + 27] &]
-
lista(nn) = for(n=1, nn, if(ispseudoprime(7*10^n+27), print1(n, ", "))); \\ Altug Alkan, Jul 05 2016
-
from sympy import isprime
def afind(limit, startk=0):
sevenpow10 = 7*10**startk
for k in range(startk, limit+1):
if isprime(sevenpow10 + 27):
print(k, end=", ")
k += 1
sevenpow10 *= 10
afind(500) # Michael S. Branicky, Dec 31 2021
a(17)-a(20) from Kamada data by
Tyler Busby, Apr 14 2024
A274679
Numbers k such that 7*10^k + 33 is prime.
Original entry on oeis.org
1, 2, 6, 10, 17, 29, 53, 107, 133, 596, 852, 1068, 1186, 1356, 1673, 1987, 3170, 3312, 5819, 6655, 19267, 20009, 29302, 72614, 170348, 178566
Offset: 1
2 is in this sequence because 7*10^2 + 33 = 733 is prime.
4 is not in the sequence because 7*10^4 + 33 = 70033 = 59 * 1187.
Initial terms and associated primes:
a(1) = 1: 103;
a(2) = 2: 733;
a(3) = 6: 7000033;
a(4) = 10: 70000000033, etc.
Cf. similar sequences listed in
A274676.
-
[n: n in [1..500] | IsPrime(7*10^n+33)];
-
Select[Range[0, 3000], PrimeQ[7 10^# + 33] &]
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lista(nn) = for(n=1, nn, if(ispseudoprime(7*10^n+33), print1(n, ", "))); \\ Altug Alkan, Jul 05 2016
a(21)-a(26) from Kamada data by
Tyler Busby, Apr 14 2024
A274700
Numbers k such that 7*10^k + 37 is prime.
Original entry on oeis.org
1, 7, 15, 21, 91, 325, 465, 853, 76717
Offset: 1
1 is in this sequence because 7*10 + 37 = 107 is prime.
3 is not in the sequence because 7*10^3 + 37 = 31*227.
Initial terms and associated primes:
a(1) = 1: 107;
a(2) = 7: 70000037;
a(3) = 15: 7000000000000037;
a(4) = 21: 7000000000000000000037;
etc.
Cf. similar sequences listed in
A274676.
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[n: n in [1..400] | IsPrime(7*10^n+37)];
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Select[Range[0, 3000], PrimeQ[7 10^# + 37] &]
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lista(nn) = for(n=1, nn, if(ispseudoprime(7*10^n+37), print1(n, ", "))); \\ Altug Alkan, Jul 05 2016
Showing 1-4 of 4 results.
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