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A078264 Integer part of the geometric mean of the forward and reverse concatenations of 1 to n. 1
1, 15, 198, 2309, 25895, 284217, 3074048, 32896079, 349188532, 11646890238, 1171148874112, 122278263238675, 12727490844526758, 1320830780128673820, 136722265049041488664, 14120912163801368446154 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..16.

FORMULA

a(n) = Floor[A078263(n)^(1/2)].

EXAMPLE

a(3) =123*321 = 39483.

PROG

(PARI) f="1"; b="1"; for(i=2, 40, print1(sqrtint(eval(f)*eval(b)), ", "); f=concat(f, Str(i)); b=concat(Str(i), b)) - Lambert Herrgesell (zero815(AT)googlemail.com), Mar 13 2006

CROSSREFS

Cf. A078263.

Sequence in context: A152587 A060337 A180789 * A322914 A014896 A048444

Adjacent sequences:  A078261 A078262 A078263 * A078265 A078266 A078267

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Nov 24 2002

EXTENSIONS

More terms from Lambert Herrgesell (zero815(AT)googlemail.com), Mar 13 2006

STATUS

approved

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Last modified March 30 18:46 EDT 2020. Contains 333127 sequences. (Running on oeis4.)