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A362117
Concatenation of first n numbers in base 5.
3
1, 12, 123, 1234, 123410, 12341011, 1234101112, 123410111213, 12341011121314, 1234101112131420, 123410111213142021, 12341011121314202122, 1234101112131420212223, 123410111213142021222324, 12341011121314202122232430, 1234101112131420212223243031
OFFSET
1,2
When regarded as decimal numbers, the first prime in this sequence is a(6) = 12341011.
a(8) is also prime and for n <= 2000, a(n) is not prime except for n = 6 or 8. - Chai Wah Wu, Apr 19 2023
MATHEMATICA
A362117[n_]:=FromDigits[Flatten[IntegerDigits[Range[n], 5]]]; Array[A362117, 20] (* Paolo Xausa, Nov 27 2023 *)
PROG
(Python)
from gmpy2 import digits
def A362117(n): return int(''.join(digits(n, 5) for n in range(1, n+1))) # Chai Wah Wu, Apr 19 2023
CROSSREFS
Sequence in context: A262575 A187871 A187869 * A262574 A159901 A159900
KEYWORD
nonn,base
AUTHOR
STATUS
approved

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Last modified September 20 15:18 EDT 2024. Contains 376072 sequences. (Running on oeis4.)