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A228829 a(n) = (m+n-k) mod (m-n+k) where k = BigOmega(n) and m is the next larger integer after n with the same k = BigOmega(m) as n. 1
0, 1, 0, 2, 3, 2, 3, 2, 4, 2, 0, 4, 0, 2, 0, 2, 0, 1, 4, 2, 0, 2, 8, 1, 3, 0, 0, 2, 9, 4, 12, 2, 1, 1, 0, 2, 0, 2, 0, 2, 3, 4, 2, 4, 3, 1, 28, 2, 4, 2, 0, 6, 4, 2, 0, 2, 4, 2, 12, 1, 0, 0, 2, 0, 1, 2, 0, 1, 6, 2, 4, 4, 4, 0, 1, 3, 14, 1, 18, 0, 0, 3, 0, 1, 0, 2, 0, 5, 4, 2, 7, 2, 1, 4, 18, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,4

COMMENTS

Let k = A001222(n) be the number of prime divisors of n and let m>n be the smallest number larger than n with the same number of prime divisors, k=A001222(m). Then a(n) = (m+n-k) mod (m-n+k).

LINKS

Table of n, a(n) for n=2..97.

EXAMPLE

a(1) is undefined because there is only 1 0-almost prime (the 1 itself).

a(2) = 0 because (3 + 2 - 1 mod 3 - 2 + 1) = (4 mod 2) = 0 where 1 < 2 < 3 and 2, 3 are consecutive 1-almost primes,

a(3) = 1 because (5 + 3 - 1 mod 5 - 3 + 1) = (7 mod 3) = 1 where 1 < 3 < 5 and 3, 5 are consecutive 1-almost primes,

a(4) = 0 because (6 + 4 - 2 mod 6 - 4 + 2) = (8 mod 4) = 0 where 1 < 4 < 6 and 4, 6 because consecutive 2-almost primes,

a(5) = 2 because (7 + 5 - 1 mod 7 - 5 + 1) = (11 mod 3) = 2 where 1 < 5 < 7 and 5, 7 are consecutive 1-almost primes,

a(6) = 3 because (9 + 6 - 2 mod 9 - 6 + 2) = (13 mod 5) = 3 where 1 < 6 < 9 and 6, 9 are consecutive 2-almost primes.

MAPLE

A228829 := proc(n)

    local k, m ;

    k := numtheory[bigomega](n) ;

    for m from n+1 do

        if numtheory[bigomega](m) = k then

            return modp(m+n-k, m-n+k)

        end if;

     end do:

end proc: # R. J. Mathar, Sep 13 2013

CROSSREFS

Cf. A226534.

Sequence in context: A069898 A245511 A259940 * A007978 A245575 A096737

Adjacent sequences:  A228826 A228827 A228828 * A228830 A228831 A228832

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Sep 04 2013

EXTENSIONS

Corrected by R. J. Mathar, Sep 13 2013

STATUS

approved

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Last modified September 16 12:38 EDT 2019. Contains 327102 sequences. (Running on oeis4.)