A373985 - OEIS

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A373985

a(n) = gcd(A108951(n), A373158(n)), where A108951 is fully multiplicative and A373158 is fully additive with a(p) = p# for prime p, where x# is the primorial A034386(x).

1, 2, 6, 4, 30, 4, 210, 2, 12, 4, 2310, 2, 30030, 4, 36, 8, 510510, 2, 9699690, 2, 36, 4, 223092870, 12, 60, 4, 18, 2, 6469693230, 2, 200560490130, 2, 12, 4, 60, 16, 7420738134810, 4, 12, 12, 304250263527210, 2, 13082761331670030, 2, 6, 4, 614889782588491410, 2, 420, 2, 36, 2, 32589158477190044730, 4, 180, 24, 36, 4

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OFFSET

1,2

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..2048

Index entries for sequences related to primorial numbers

FORMULA

a(n) = gcd(A373158(n), A373984(n)).

a(n) = A108951(n) / A373987(n).

For n >= 2, a(n) = A373158(n) / A373986(n).

For n >= 1, a(A000040(n)) = A002110(n).

PROG

(PARI) A373985(n) = { my(f=factor(n), m=1, s=0); for(i=1, #f~, my(x=prod(i=1, primepi(f[i, 1]), prime(i))); s += f[i, 2]*x; m *= x^f[i, 2]); gcd(m, s); };

CROSSREFS

Cf. A000040, A002110, A034386, A108951, A373158, A373984, A373986, A373987.

Sequence in context: A226532 A335049 A006233 * A164020 A326579 A057643

Adjacent sequences: A373982 A373983 A373984 * A373986 A373987 A373988

KEYWORD

nonn

AUTHOR

Antti Karttunen, Jun 25 2024

STATUS

approved