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A078326 Numbers n such that n-1 and n are a pair of consecutive powerful numbers. 3
9, 289, 676, 9801, 12168, 235225, 332929, 465125, 1825201, 11309769, 384199201, 592192225, 4931691076, 5425069448, 13051463049, 221322261601, 443365544449, 865363202001, 8192480787001, 11968683934832, 13325427460801, 15061377048201, 28821995554248 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) = u*rad(u) = v*rad(v)+1 for appropriate u, v, where rad(n) =

A007947(n) is the squarefree kernel.

Also numbers n such that n(n-1) is a powerful number. - Charles R Greathouse IV, Aug 08 2013

LINKS

Donovan Johnson, Table of n, a(n) for n = 1..39 (terms < 10^22)

Eric Weisstein's World of Mathematics, Powerful Number

FORMULA

a(n) = A060355(n)+1.

PROG

(PARI) is(n)=ispowerful(n-1)&&ispowerful(n) \\ Charles R Greathouse IV, Aug 08 2013

CROSSREFS

Cf. A078310, A064549, A078315, A078325, A060355, A078326.

Sequence in context: A012141 A110553 * A118893 A055792 A053935 A086699

Adjacent sequences:  A078323 A078324 A078325 * A078327 A078328 A078329

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Nov 23 2002

EXTENSIONS

a(22)-a(23) from Donovan Johnson, Jul 29 2011

STATUS

approved

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Last modified August 17 17:05 EDT 2018. Contains 313816 sequences. (Running on oeis4.)