Original entry on oeis.org
2, 1, 2, 2, 7, 10, 101, 196, 9, 550, 6150, 4532, 3249, 12360, 8719
Offset: 1
Cf.
A110774,
A110776,
A110777,
A110778,
A112534,
A110780,
A110781,
A110782,
A110783,
A110788,
A110789
-
from sympy import isprime
from itertools import count, islice
def agen(): # generator of terms
s = ""
while True:
for d in "13":
for k in count(1):
if isprime(int(s+d*k)): break
yield k
s += d*k
print(list(islice(agen(), 10))) # Michael S. Branicky, Aug 23 2022
A110776
Copies of 1 and 7 alternately such that every partial concatenation is a prime.
Original entry on oeis.org
11, 777, 11, 777777, 111111111, 7777777777777777777777777, 111111111, 777
Offset: 1
11, 11777, 1177711, ... are all prime.
Cf.
A110774,
A110775,
A110777,
A110778,
A112534,
A110780,
A110781,
A110782,
A110783,
A110788,
A110789.
The next term has 762 1's and is too large to include.
A110778
Copies of 3 and 7 alternately such that every partial concatenation is a prime.
Original entry on oeis.org
3, 7, 3, 777, 333, 777777777777777777777, 3333333, 7777777777777777777777777777777, 33333
Offset: 1
3, 37, 373, 373777, ... are all prime.
-
id[n_]:=IntegerDigits[n]; f[x_,y_]:=FromDigits[Flatten[Append[{x},y]]]; a[x_,y_]:=NestWhile[f[id[#],y]&,f[id[x],y],!PrimeQ[#]&]; d[x_, y_]:=x-FromDigits[PadRight[id[y],Length[id[x]]]]; t={3}; x=3; Do[y=a[x,7]; AppendTo[t,d[y,x]]; x=a[y,3]; AppendTo[t,d[x,y]],{n,4}]; t (* Jayanta Basu, May 20 2013 *)
The next term has 480 7's and is too large to include.
A110780
Copies of 1 and 9 alternately such that every partial concatenation is a prime.
Original entry on oeis.org
11, 99999, 111111111, 9999999999, 11111111111111111111111111111111111111, 99999999999999999999999999999999999999999999999
Offset: 1
11, 1199999, 1199999111111111, ... are all prime.
The next term has more than 800 1's and is too large to include.
Original entry on oeis.org
2, 3, 2, 6, 9, 25, 9, 3, 762, 354, 248, 2181, 606, 1941, 6423, 11871
Offset: 1
Cf.
A110774,
A110775,
A110776,
A110778,
A112534,
A110780,
A110781,
A110782,
A110783,
A110788,
A110789
-
from sympy import isprime
from itertools import count, islice
def agen(): # generator of terms
s = ""
while True:
for d in "17":
for k in count(1):
if isprime(int(s+d*k)): break
yield k
s += d*k
print(list(islice(agen(), 11))) # Michael S. Branicky, Aug 23 2022
Original entry on oeis.org
2, 5, 9, 10, 38, 47, 1279, 11389
Offset: 1
-
from sympy import isprime
from itertools import count, islice
def agen(): # generator of terms
s = ""
while True:
for d in "19":
for k in count(1):
if isprime(int(s+d*k)): break
yield k
s += d*k
print(list(islice(agen(), 7))) # Michael S. Branicky, Aug 24 2022
A110782
Copies of 1,3,7 and 9 cyclically such that every partial concatenation is a prime.
Original entry on oeis.org
11, 3, 777, 999, 11, 33333333, 777777777777777777777, 999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999999, 1111111111111111111111111
Offset: 1
11, 113, 113777, 113777999, ... are all prime.
The next term is 726 3's and is too large to include.
Original entry on oeis.org
2, 1, 3, 3, 2, 8, 21, 102, 25, 726, 954, 16522, 2939, 10691, 8157
Offset: 1
-
from sympy import isprime
from itertools import count, islice
def agen(): # generator of terms
s = ""
while True:
for d in "1379":
for k in count(1):
if isprime(int(s+d*k)): break
yield k
s += d*k
print(list(islice(agen(), 11))) # Michael S. Branicky, Aug 24 2022
A110788
Copies of 7 and 1 alternately such that every partial concatenation is a prime.
Original entry on oeis.org
7, 1, 77, 1111, 77777, 1111111111, 77777777777777777777777, 111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111
Offset: 1
7, 71, 7177, 71771111, ... are all prime.
Original entry on oeis.org
1, 1, 2, 4, 5, 10, 23, 102, 102, 138, 451, 1922, 1624, 5630, 26410
Offset: 1
-
from sympy import isprime
from itertools import count, islice
def agen(): # generator of terms
s = ""
while True:
for d in "71":
for k in count(1):
if isprime(int(s+d*k)): break
yield k
s += d*k
print(list(islice(agen(), 11))) # Michael S. Branicky, Aug 23 2022
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