A280821 -id:A280821 - cp's OEIS frontend

A280820 Partial sums of A001783.

1, 2, 4, 7, 31, 36, 756, 861, 3101, 3290, 3632090, 3632475, 482634075, 482653380, 483550276, 485577301, 20923275465301, 20923275550386, 6423296981278386, 6423296990008107, 6423344287544107, 6423345537481432, 1124007151123145161432, 1124007151123182343577

Offset: 1

Jaroslav Krizek, Jan 08 2017

nonn

A001783(n) = the product of totatives of n.

Cf. A001783, A280821.

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

Accumulate@ Table[Times @@ Select[Range@ n, CoprimeQ[n, #] &], {n, 24}] (* Michael De Vlieger, Jan 09 2017 *)

a(n) = Sum_{i=1..n} A001783(i).

A281027 Partial products of A066570.

Original entry on oeis.org

1, 2, 6, 48, 240, 34560, 241920, 92897280, 15049359360, 288947699712000, 3178424696832000, 3954468870810501120000, 51408095320536514560000, 232150733172291613910630400000, 338475768965201173081699123200000000, 3493719809197289292455451813740544000000000

Offset: 1

Jaroslav Krizek, Jan 19 2017

nonn

Cf. A066570(n) = the product of cototatives of n.

Cf. A000178, A280821, A281025.

[1] cat [&*[&*[h: h in [2..k] | GCD(h,k) ne 1]: k in [2..n]]: n in [2..100]];

FoldList[Times, Table[Times @@ Select[Range[2, n], ! CoprimeQ[n, #] &], {n, 1, 16}]] (* Amiram Eldar, Aug 16 2025 *)

a(n) = Product_{i=1..n} A066570(i).

a(n) = A000178(n)/A280821(n). - Amiram Eldar, Aug 16 2025

cp's OEIS Frontend

A280820 Partial sums of A001783.

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