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A237881
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a(n) = 2-adic valuation of prime(n)+prime(n+1).
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1
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0, 3, 2, 1, 3, 1, 2, 1, 2, 2, 2, 1, 2, 1, 2, 4, 3, 7, 1, 4, 3, 1, 2, 1, 1, 2, 1, 3, 1, 4, 1, 2, 2, 5, 2, 2, 6, 1, 2, 5, 3, 2, 7, 1, 2, 1, 1, 1, 3, 1, 3, 5, 2, 2, 3, 2, 2, 2, 1, 2, 6, 3, 1, 4, 1, 3, 2, 2, 3, 1, 3, 1, 2, 4, 1, 2, 1, 1, 1, 2, 3, 2, 5, 3, 1, 2, 1, 1, 2, 1, 1, 1, 1, 1, 1, 2, 1, 2, 3, 6, 4, 5, 2, 2, 2, 2, 2, 3, 4, 3, 2, 1, 2, 1, 3, 2, 1, 2, 5, 3, 1, 1, 4
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OFFSET
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1,2
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LINKS
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FORMULA
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EXAMPLE
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a(5)=3 because prime(5)=11, prime(6)=13, 11+13=24=2^3*3, 2-adic valuation(24)=3.
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MATHEMATICA
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IntegerExponent[ListConvolve[{1, 1}, Prime[Range[200]]], 2] (* Paolo Xausa, Nov 02 2023 *)
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PROG
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(PARI) {for(i=1, 200, k=valuation(prime(i)+prime(i+1), 2); print1(k, ", "))}
(Python)
from sympy import prime
def A237881(n): return (~(m:=prime(n)+prime(n+1))&m-1).bit_length() # Chai Wah Wu, Jul 08 2022
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CROSSREFS
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KEYWORD
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nonn,easy
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AUTHOR
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STATUS
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approved
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