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A196520 Smallest Friedman number of order n. 0
25, 279936, 31381059609, 1125899906842624, 1152921504606846976, 4722366482869645213696, 42391158275216203514294433201, 324518553658426726783156020576256 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

More terms from a=9 to a=12 are 22528399544939174411840147874772641, 147808829414345923316083210206383297601, 1427247692705959881058285969449495136382746624 and 91343852333181432387730302044767688728495783936.

LINKS

Table of n, a(n) for n=1..8.

Erich Friedman, Problem of the Month May 2010

FORMULA

All numbers of this kind are perfect powers.

EXAMPLE

Since 25 is the smallest Friedman number, it is the smallest Friedman number of order 1.

279936 = 6^7 = (9 - 3)^(9 - 2), together using the digits of the number itself. Hence it is the smallest Friedman number of order 2.

31381059609 = 9^11 = 9^(5+6) = 3^(30-8+0), together using the digits of the number itself. Hence it is the smallest Friedman number of order 3.

CROSSREFS

Cf. A036057

Sequence in context: A151649 A122500 A251362 * A228536 A191559 A279039

Adjacent sequences:  A196517 A196518 A196519 * A196521 A196522 A196523

KEYWORD

nonn,base

AUTHOR

Kausthub Gudipati, Oct 03 2011

STATUS

approved

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Last modified October 16 16:08 EDT 2019. Contains 328101 sequences. (Running on oeis4.)