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A318305 a(n) = product_{p} - product_{p-1}, where p are distinct primes dividing n; a(n) = A007947(n) - A173557(n). 5
0, 1, 1, 1, 1, 4, 1, 1, 1, 6, 1, 4, 1, 8, 7, 1, 1, 4, 1, 6, 9, 12, 1, 4, 1, 14, 1, 8, 1, 22, 1, 1, 13, 18, 11, 4, 1, 20, 15, 6, 1, 30, 1, 12, 7, 24, 1, 4, 1, 6, 19, 14, 1, 4, 15, 8, 21, 30, 1, 22, 1, 32, 9, 1, 17, 46, 1, 18, 25, 46, 1, 4, 1, 38, 7, 20, 17, 54, 1, 6, 1, 42, 1, 30, 21, 44, 31, 12, 1, 22, 19, 24, 33, 48, 23, 4, 1, 8 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

LINKS

Antti Karttunen, Table of n, a(n) for n = 1..16384

FORMULA

a(n) = A051953(n)/A003557(n) = A007947(n) - A173557(n) = A173557(n) - A318304(n).

EXAMPLE

For n = 45 = 3^2 * 5, the prime factors are 3 and 5, thus a(45) = (3*5) - (2*4) = 15 - 8 = 7.

PROG

(PARI)

A003557(n) = { my(f=factor(n)); for (i=1, #f~, f[i, 2] = f[i, 2]-1); factorback(f); }; \\ From A003557

A051953(n) = (n - eulerphi(n));

A318305(n) = A051953(n)/A003557(n);

(PARI)

A007947(n) = factorback(factorint(n)[, 1]); \\ From A007947

A173557(n) = my(f=factor(n)[, 1]); prod(k=1, #f, f[k]-1); \\ From A173557

A318305(n) = (A007947(n) - A173557(n));

CROSSREFS

Cf. A003557, A007947, A051953, A083254, A173557, A318304.

Sequence in context: A162400 A179054 A063928 * A306264 A321647 A323410

Adjacent sequences:  A318302 A318303 A318304 * A318306 A318307 A318308

KEYWORD

nonn

AUTHOR

Antti Karttunen, Aug 26 2018

STATUS

approved

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Last modified May 26 19:44 EDT 2019. Contains 323597 sequences. (Running on oeis4.)