A038541 - OEIS

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A038541

a(n) = number of modules with n elements over the ring of integers in the imaginary quadratic field of discriminant -20.

20

1, 1, 2, 2, 1, 2, 2, 3, 5, 1, 0, 4, 0, 2, 2, 5, 0, 5, 0, 2, 4, 0, 2, 6, 2, 0, 10, 4, 2, 2, 0, 7, 0, 0, 2, 10, 0, 0, 0, 3, 2, 4, 2, 0, 5, 2, 2, 10, 5, 2, 0, 0, 0, 10, 0, 6, 0, 2, 0, 4, 2, 0, 10, 11, 0, 0, 2, 0, 4, 2, 0, 15, 0, 0, 4, 0, 0, 0, 0, 5, 20, 2, 2, 8, 0, 2, 4, 0, 2, 5, 0, 4, 0, 2, 0, 14

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OFFSET

1,3

COMMENTS

Equivalently, number of modules with n elements over the ring Z[sqrt(-5)].

See A352550 for comments and PARI code.

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..10000

CROSSREFS

Cf. A038540, A038541, A248107, A352550-A352567.

Sequence in context: A226983 A112175 A112206 * A070215 A071457 A227782

Adjacent sequences: A038538 A038539 A038540 * A038542 A038543 A038544

KEYWORD

nonn,mult

AUTHOR

Paolo Dominici (pl.dm(AT)libero.it)

EXTENSIONS

Edited by M. F. Hasler, Feb 18 2022

Revised by N. J. A. Sloane, Mar 21 2022

STATUS

approved