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 A237881 a(n) = 2-adic valuation of prime(n)+prime(n+1). 1
 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 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Charles R Greathouse IV, Table of n, a(n) for n = 1..10000 FORMULA a(n) = A007814(A001043(n)). a(n) << log n; in particular, a(n) <= log_2 n + log_2 log n + O(1). - Charles R Greathouse IV, Feb 14 2014 EXAMPLE a(5)=3 because prime(5)=11, prime(6)=13, 11+13=24=2^3*3, 2-adic valuation(24)=3. MATHEMATICA IntegerExponent[ListConvolve[{1, 1}, Prime[Range[200]]], 2] (* Paolo Xausa, Nov 02 2023 *) PROG (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 CROSSREFS Cf. A071087, A098048. Sequence in context: A085068 A265027 A079587 * A112745 A205564 A036585 Adjacent sequences: A237878 A237879 A237880 * A237882 A237883 A237884 KEYWORD nonn,easy AUTHOR Antonio Roldán, Feb 14 2014 STATUS approved

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Last modified June 13 00:21 EDT 2024. Contains 373362 sequences. (Running on oeis4.)