VOOZH about

URL: https://oeis.org/A379865

⇱ A379865 - OEIS

login
A379865
Number of base 10 digits of 2^(p-1)*(2^p-1) where p = prime(n).
1
1, 2, 3, 4, 7, 8, 10, 12, 14, 18, 19, 22, 25, 26, 28, 32, 36, 37, 41, 43, 44, 48, 50, 54, 59, 61, 62, 65, 66, 68, 77, 79, 83, 84, 90, 91, 95, 98, 101, 104, 108, 109, 115, 116, 119, 120, 127, 134, 137, 138, 140, 144, 145, 151, 155, 159, 162, 163, 167, 169, 171, 177
OFFSET
1,2
FORMULA
a(n) = A055642(A060286(n)).
MATHEMATICA
A379865[n_] := IntegerLength[2^(# - 1)*(2^# - 1)] & [Prime[n]];
Array[A379865, 100] (* Paolo Xausa, Jan 08 2025 *)
PROG
(Python)
from sympy import prime
def a(n):
p = prime(n)
return len(str((1 << (p-1)) * ((1 << p) - 1)))
print([a(n) for n in range(1, 63)])
CROSSREFS
KEYWORD
nonn,easy,base
AUTHOR
Darío Clavijo, Jan 04 2025
STATUS
approved