A291373 a(n) is the smallest number k such that A001065(k) = A002110(n), or 0 if no such k exists.

2, 0, 6, 841, 0, 1722, 30018, 0, 0, 0, 4057230930, 0, 0, 92568222856376123089883329681

Offset

0,1

Comments

For n in A057704, 0 < a(n) <= (A002110(n)-1)^2. - Max Alekseyev, Sep 01 2025

Links

Table of n, a(n) for n=0..13.

Formula

a(n) = A070015(A002110(n)). - Michel Marcus, Aug 25 2017

Example

a(5) = 1722 because sigma(1722) - 1722 = 2*3*5*7*11 = A002110(5) and 1722 is the least number with this property.

Crossrefs

Cf. A001065, A002110, A057704, A070015, A116017, A153076, A235710, A244444, A279359, A291356, A378099.

Sequence in context: A305620 A294470 A283654 * A342700 A021487 A369745

Adjacent sequences: A291370 A291371 A291372 * A291374 A291375 A291376

Keyword

nonn,hard,more

Author

Altug Alkan, Aug 23 2017

Extensions

a(7) and a(10) from Giovanni Resta, Aug 23 2017

a(8)-a(9), a(11)-a(13) from Max Alekseyev, Sep 04 2025

Status

approved