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A020479 Number of noninvertible 2 X 2 matrices over Z/nZ (determinant is a divisor of 0). 1
10, 33, 160, 145, 1008, 385, 2560, 2673, 7120, 1441, 16128, 2353, 26320, 27585, 40960, 5185, 81648, 7201, 113920, 97713, 155056, 12673, 258048, 90625, 299728, 216513, 421120, 25201, 671760, 30721, 655360, 552321, 866320, 532945, 1306368, 51985 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

LINKS

Table of n, a(n) for n=2..37.

FORMULA

a(n) seems to be divisible by n. - Ralf Stephan, Sep 01 2003

a(n)=n^4-A000252(n). - T. D. Noe, Jan 16 2006

CROSSREFS

Sequence in context: A094170 A004638 A211033 * A219818 A264251 A140866

Adjacent sequences:  A020476 A020477 A020478 * A020480 A020481 A020482

KEYWORD

nonn

AUTHOR

David W. Wilson

STATUS

approved

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Last modified September 22 11:29 EDT 2020. Contains 337289 sequences. (Running on oeis4.)