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A036898 List of pairs of consecutive refactorable numbers. 10
1, 2, 8, 9, 1520, 1521, 50624, 50625, 62000, 62001, 103040, 103041, 199808, 199809, 221840, 221841, 269360, 269361, 463760, 463761, 690560, 690561, 848240, 848241, 986048, 986049, 1252160, 1252161, 1418480, 1418481, 2169728, 2169729, 2692880 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Donovan Johnson, Table of n, a(n) for n = 1..2000

S. Colton, Refactorable Numbers - A Machine Invention, J. Integer Sequences, Vol. 2, 1999, #2.

S. Colton, HR - Automatic Theory Formation in Pure Mathematics

EXAMPLE

8 is refactorable because tau(8)=4 and 4 divides 8.

9 is refactorable because tau(9)=3 and 3 divides 9.

PROG

(PARI) isrefac(n) = ! (n % numdiv(n));

lista(nn) = {for (n = 1, nn, if (isrefac(n) && isrefac(n+1), print1(n, ", ", n+1, ", ")); ); } \\ Michel Marcus, Aug 31 2013

CROSSREFS

Cf. A033950, A114617.

Sequence in context: A091793 A109351 A111134 * A053372 A088155 A005876

Adjacent sequences:  A036895 A036896 A036897 * A036899 A036900 A036901

KEYWORD

nonn

AUTHOR

Simon Colton (simonco(AT)cs.york.ac.uk)

STATUS

approved

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Last modified May 21 08:52 EDT 2019. Contains 323441 sequences. (Running on oeis4.)