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A318272
a(n) is the least k such that A049417(A049417(k)) = n*k, where A049417 is the infinitary sigma function, or 0 if no such k exists.
1
1, 2, 8, 15, 24, 60, 1321920, 17850, 285600, 763776
OFFSET
1,2
COMMENTS
It is also known that a(12) = 71400.
Then for higher indices n, we have:
a(11) <= 414230544000;
a(13) <= 2667897127526400;
a(14) <= 446464417259520;
a(15) <= 23613006957281280;
a(16) <= 22227004800;
a(17) <= 3134896756992000;
a(18) <= 15414516736819200;
a(20) <= 53129265653882880.
a(16) = 8420630400. - Giovanni Resta, Aug 25 2018
LINKS
Tomohiro Yamada, Infinitary superperfect numbers, Annales Mathematicae et Informaticae, 47 (2017) pp. 211-218. See Table 1.
CROSSREFS
Cf. A272930 (analog for sigma), A318242 (analog for bi-unitary sigma).
Sequence in context: A063286 A133230 A318242 * A244476 A292202 A189952
KEYWORD
nonn,more
AUTHOR
Michel Marcus, Aug 23 2018
STATUS
approved