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A243296 Exponent of 2 in (A002110(n)/2)^2-1 1
3, 5, 4, 3, 4, 4, 3, 3, 4, 4, 3, 3, 4, 4, 3, 5, 3, 4, 5, 4, 4, 3, 3, 3, 8, 4, 3, 4, 4, 4, 3, 3, 6, 3, 3, 4, 3, 3, 4, 3, 4, 4, 4, 3, 3, 6, 7, 3, 5, 4, 4, 4, 3, 3, 3, 5, 9, 3, 3, 6, 3, 7, 4, 9, 3, 6, 5, 3, 6, 7, 4, 4, 3, 5, 5, 3, 5, 7, 4, 3, 4, 4, 4, 5, 3 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

COMMENTS

a(n) >= 3, = 3 if A002110(n) == 6 or 10 mod 16.

Whenever A000040(n) is in A003629, at least one of a(n) and a(n+1) is 3.

LINKS

Robert Israel, Table of n, a(n) for n = 2..10000

MathOverflow question On quantities with no very small odd prime factors; a response to Wlodzimierz Holsztynski

EXAMPLE

A002110(2) = 2*3 = 6 and (6/2)^2-1 = 8 = 2^3 so a(2) = 3.

MAPLE

N:= 1000; # to get a(2) to a(N)

P:= 1:

for n from 2 to N do

  P:= P * ithprime(n);

  A[n]:= padic[ordp](P^2-1, 2);

od:

seq(A[n], n=2..N); # Robert Israel, Jun 02 2014

CROSSREFS

Cf. A002110.

Sequence in context: A075077 A196771 A266121 * A081361 A195132 A086181

Adjacent sequences:  A243293 A243294 A243295 * A243297 A243298 A243299

KEYWORD

nonn

AUTHOR

Robert Israel, Jun 02 2014

STATUS

approved

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Last modified November 13 15:41 EST 2019. Contains 329106 sequences. (Running on oeis4.)