A280458 Partial products of A023896.

1, 1, 3, 12, 120, 720, 15120, 241920, 6531840, 130636800, 7185024000, 172440576000, 13450364928000, 564915326976000, 33894919618560000, 2169274855587840000, 295021380359946240000, 15931154539437096960000, 2724227426243743580160000, 217938194099499486412800000

Offset

1,3

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 (sum of totatives of n), A213544 (partial sums of A023896).

Sequence in context: A133987 A359658 A194506 * A294198 A133553 A010571

Adjacent sequences: A280455 A280456 A280457 * A280459 A280460 A280461

Keyword

nonn

Author

Jaroslav Krizek, Jan 03 2017

Status

approved