

A242033


a(n)=lpf(A245024(n)1), where lpf=least prime factor (A020639).


9



3, 3, 3, 5, 3, 3, 3, 3, 7, 3, 5, 3, 3, 3, 3, 3, 5, 3, 7, 3, 3, 3, 3, 5, 3, 3, 3, 7, 3, 3, 5, 3, 3, 3, 3, 13, 3, 5, 3, 3, 3, 3, 3, 5, 3, 3, 3, 3, 3, 5, 3, 3, 3, 11, 3, 7, 3, 5, 3, 3, 3, 3, 3, 5, 3, 7, 3, 3, 3, 11, 3, 5, 3, 3, 3, 7, 3, 3, 5, 3, 19, 3, 3, 3, 3, 5
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OFFSET

1,1


COMMENTS

Conjecture. The sequence contains all odd primes.
The conjecture is true. Consider n1 = p*q where p is an odd prime and q is a prime > p such that q == p^(1) mod r for every odd prime r < p. Such primes q exist by Dirichlet's theorem on primes in arithmetic progressions.  Robert Israel, Aug 13 2014


LINKS

Table of n, a(n) for n=1..86.


MAPLE

lpf:= n > min(numtheory:factorset(n)):
L:= [seq(lpf(2*i+1), i=1..1000)]:
L[select(i>L[i] < L[i1], [$2..nops(L)])]; # Robert Israel, Aug 13 2014


MATHEMATICA

lpf[n_]:=lpf[n]=First[First[FactorInteger[n]]]; (*lesat prime factor*)A242033=Map[lpf[#1]&, Select[Range[6, 300, 2], lpf[#1]<lpf[#3]&](*A245024*)] (* Peter J. C. Moses, Aug 14 2014 *)


CROSSREFS

Cf. A245024, A243937, A242034, A020639.
Sequence in context: A123371 A011277 A084742 * A301738 A302387 A049613
Adjacent sequences: A242030 A242031 A242032 * A242034 A242035 A242036


KEYWORD

nonn


AUTHOR

Vladimir Shevelev, Aug 12 2014


EXTENSIONS

More terms from Peter J. C. Moses, Aug 12 2014


STATUS

approved



