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A072021 Smallest solution to gcd(x, reverse(x)) = 5^n. 5
5, 5200, 521000, 5213750, 521875, 5218750, 52130234375, 5734841796875, 57869714843750, 526046650390625, 5265674365234375, 52187008544921875, 526515306396484375, 5213023309008789062500, 5213596736358642578125, 5260466086273193359375, 526041911745452880859375 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Hiroaki Yamanouchi, Table of n, a(n) for n = 1..25

FORMULA

a(n) = A069554(5^n).

EXAMPLE

For n = 4, gcd(521875, 578125) = 3125 = 5^4.

For n = 8, a(8) = 5734841796875 = 5^9*2936239, reverse(a(8)) = 5786971484375 = 5^8*71*208657.

PROG

(PARI) a(n) = {my(k = 1); while (gcd(k, fromdigits(Vecrev(digits(k)))) != 5^n, k++); k; } \\ Michel Marcus, Jul 13 2018

CROSSREFS

Cf. A004086, A055483, A069554, A071686, A072005, A072050, A072016-A072018.

Sequence in context: A276238 A086896 A177503 * A196627 A013535 A079812

Adjacent sequences:  A072018 A072019 A072020 * A072022 A072023 A072024

KEYWORD

nonn,base

AUTHOR

Labos Elemer, Jun 06 2002

EXTENSIONS

a(9)-a(18) from Hiroaki Yamanouchi, Sep 10 2014

STATUS

approved

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Last modified May 5 23:41 EDT 2021. Contains 343579 sequences. (Running on oeis4.)