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A280458 Partial products of A023896. 0
1, 1, 3, 12, 120, 720, 15120, 241920, 6531840, 130636800, 7185024000, 172440576000, 13450364928000, 564915326976000, 33894919618560000, 2169274855587840000, 295021380359946240000, 15931154539437096960000, 2724227426243743580160000, 217938194099499486412800000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

A023896(n) = the sum of totatives of n.

a(n) = n! for n = 1, 5 and 6.

LINKS

Table of n, a(n) for n=1..20.

FORMULA

a(n) = Sum_{i=1..n} A023896(i).

MATHEMATICA

FoldList[#1 #2 &, Table[Ceiling[(n EulerPhi@ n)/2], {n, 20}]] (* Michael De Vlieger, Jan 03 2017 *)

PROG

(MAGMA) [&*[&+[h: h in [1..k] | GCD(h, k) eq 1]: k in [1..n]]: n in [1..100]]

CROSSREFS

Cf. A023896, A213544 (partial sums of A023896).

Sequence in context: A009254 A133987 A194506 * A294198 A133553 A010571

Adjacent sequences:  A280455 A280456 A280457 * A280459 A280460 A280461

KEYWORD

nonn

AUTHOR

Jaroslav Krizek, Jan 03 2017

STATUS

approved

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Last modified July 24 14:51 EDT 2021. Contains 346273 sequences. (Running on oeis4.)