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A213018 Largest possible right-truncatable base n semiprime, written in decimal notation. 2
349859, 96614184696363331, 21453921664462866568480385, 5396625577204731352098054139, 1230847457959658263441326143300761, 95861957783594714393831931415189937897, 246968512564969427282294385793684699270364003, 2275670244821939317343219562642735197101789412250091, 452359410421075824795509870868069265597540337861667320077 (list; graph; refs; listen; history; text; internal format)
OFFSET

5,1

COMMENTS

For the definition of a right-truncatable semiprime, see A213017. The process of truncating at the right end of the digit string has to be applied to the base-n representation given in the examples. a(10) was found by S.S. Gupta. All other terms have been computed by Hermann Jurksch.

LINKS

Table of n, a(n) for n=5..13.

EXAMPLE

a(5)=349859=42143414 in base 5 = 89*3931

4214341 in base 5 = 69971 = 11*6361

421434 in base 5 = 13994 = 2*6997

42143 in base 5 = 2798 = 2*1399

4214 in base 5 = 559 = 13*43

421 in base 5 = 111 = 3*37

42 in base 5 = 22 = 2*11

4 in base 5 = 4 = 2*2

a(6)=4223145115415551545111 in base 6

a(7)=644324264233631242462662622646 in base 7

a(8)=4267773725372537135533515117773 in base 8

a(9)=43741424882428682844851886888222774 in base 9

a(10)=95861957783594714393831931415189937897 in base 10

a(11)=4567476a2738a828994aa851a116aa886a95686a231 in base 11

a(12)=43a2971ba155719171a2b1b97777775b779a732b755572b7 in base 12

a(13)=9114448462c6c46b3c9937446466b43686a24668666732c4356 in base 13

CROSSREFS

Cf. A213017

Sequence in context: A166263 A069314 A022208 * A274245 A274254 A122036

Adjacent sequences:  A213015 A213016 A213017 * A213019 A213020 A213021

KEYWORD

nonn,base,hard

AUTHOR

Hugo Pfoertner, Jun 26 2012

STATUS

approved

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Last modified July 20 01:17 EDT 2019. Contains 325168 sequences. (Running on oeis4.)