A353561 Prime shadows of colossally abundant numbers, A004490.

2, 4, 6, 12, 20, 30, 60, 84, 168, 336, 528, 880, 1320, 2640, 5280, 10560, 12480, 24960, 49920, 74880, 104832, 209664, 419328, 838656, 1096704, 2193408, 4386816, 8773632, 14622720, 29245440, 58490880, 116981760, 233963520, 350945280, 701890560, 784465920, 1568931840, 2465464320, 4930928640, 9861857280, 14792785920

Offset: 1

Author

Antti Karttunen, Apr 29 2022

Keywords

• nonn

Comments

Sequence is injective (no duplicate values occur) because A004490 is a subsequence of A025487.

Links

• Amiram Eldar, Table of n, a(n) for n = 1..3367

Crossrefs

Cf. A004490, A025487, A122111, A181819, A342012.

Cf. also A353562, A353568.

Programs

PARI

v004490 = readvec("b004490_to.txt"); \\ Prepared from b-file of A004490 with gawk ' { print $2 } '
A004490(n) = v004490[n];
A181819(n) = factorback(apply(e->prime(e),(factor(n)[,2])));
A353561(n) = A181819(A004490(n));

Formula

a(n) = A181819(A004490(n)).

a(n) = A122111(A342012(n)).