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A058022 Difference between lcm(1,..,n) and the largest prime before lcm(1,..,n) where n runs over the prime powers A000961, LCMs are in A051451. 1
3, 4, 1, 1, 1, 1, 1, 17, 19, 23, 17, 43, 1, 1, 29, 41, 1, 43, 1, 43, 47, 83, 1, 83, 61, 149, 1, 97, 89, 109, 113, 103, 113, 89, 137, 1, 157, 181, 239, 139, 241, 139, 179, 233, 193, 163, 241, 173, 283, 167, 271, 193, 277, 181, 179, 199, 1, 193, 223, 239, 239, 233, 751 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Note that a(1) = 3 and a(2) = 4 use -2 as the preceding prime. - Robert Israel, Nov 18 2015

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..1000

EXAMPLE

6th and 7th different values of LCM-s are 840 and 2520. Deviation of immediate preceding primes(839,2503) are:1 and 17. For n=1 LCM[1]=1 and prime=-2 is the largest with deviation 3. So the sequence starts with 3.

MAPLE

f:= proc(n) local m;

    m:= ilcm($1..n);

    if m < 3 then m + 2

    else  m - prevprime(m)

    fi

end proc:

A000961:= select(t -> nops(numtheory:-factorset(t))<=1, [$1..1000]):

map(f, A000961); # Robert Israel, Nov 18 2015

PROG

(PARI) N=2; print1("3, 4"); for(n=3, 1e3, if(isprimepower(n, &p), N*=p; print1(", "N-precprime(N-1)))) \\ Charles R Greathouse IV, Nov 18 2015

CROSSREFS

Cf. A000961, A003418, A051451.

Sequence in context: A201930 A176979 A299989 * A215202 A139344 A137925

Adjacent sequences:  A058019 A058020 A058021 * A058023 A058024 A058025

KEYWORD

nonn

AUTHOR

Labos Elemer, Nov 15 2000

STATUS

approved

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Last modified July 9 14:56 EDT 2020. Contains 335543 sequences. (Running on oeis4.)