STATUS
editing
approved
The OEIS is supported by the many generous donors to the OEIS Foundation.
editing
approved
a(n) is the first smallest number m such that sigma(m) is the n-th power of 22, that is, sigma(m)=22^n, or 0 if m does not exist.
a(4)=136647=3^4*7*241 since sigma(3^4*7*241)=(11^2)(2^3)(2*11^2)=2^4*11^4 and 136647 is the first smallest such number.
approved
editing
Max Alekseyev, <a href="/A180460/b180460_2.txt">Table of n, a(n) for n = 0..100</a>
editing
approved
1, 0, 0, 10363, 136647, 3018141, 66411009, 1636922343, 31276995183, 688217286267, 15200749439001, 324029599659171, 7264291502741679, 160447401116572437, 3530475812620849113, 75514126111770824037, 1662716417771040164631, 36586320846189859358019, 804905851136700392012493, 17704604426749226872106319
Max Alekseyev, <a href="/A180460/b180460_2.txt">Table of n, a(n) for n = 0..50100</a>
approved
editing
Max Alekseyev, <a href="/A180460/b180460_1.txt">Table of n, a(n) for n = 0..50</a>
editing
approved
1, 0, 0, 10363, 136647, 3018141, 66411009, 1636922343, 31276995183, 688217286267, 15200749439001, 324029599659171, 7264291502741679, 160447401116572437, 3530475812620849113, 75514126111770824037, 1662716417771040164631, 36586320846189859358019, 804905851136700392012493
William A. Tedeschi, Max Alekseyev, <a href="/A180460/b180460_1.txt">Table of n, a(n) for n = 0..3650</a>
Terms a(37) onward (in b-file) from Max Alekseyev, Mar 04 2014
approved
editing
a(n) is the first number m such that sigma(m) is the nth n-th power of 22, that is, sigma(m)=22^n, or 0 if m does not exist.
_Walter A. Kehowski (wkehowski(AT)cox.net), _, Sep 06 2010