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A159078 Number of perfect powers with distinct digits in base n. 0
1, 1, 9, 8, 25, 50, 88, 297, 657, 1418, 3212, 8662, 24185, 64103, 183718 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,3

LINKS

Table of n, a(n) for n=2..16.

EXAMPLE

The 8 powers with unique digits in base 5 are 1, 4, 8, 9, 16, 27, 144, and 576; in base 5 these are 1, 4, 13, 14, 31, 102, 1304, and 4301.

PROG

(PARI) okdigs(digs) = {for (i = 1, #digs-1, for (j = i+1, #digs, if (digs[j] == digs[i], return (0); ); ); ); return (1); }

a(n) = {b = n; sols = Set([1]); vmax = b^b; pmax = ceil(log(vmax)/log(2)); for (p = 2, pmax, i = 2; while ((iep = i^p) < vmax, if (okdigs(digits(iep, b)), sols = Set(concat(sols, iep)); ); i++; ); ); #sols; } \\ Michel Marcus, Aug 19 2013

CROSSREFS

Cf. A075309

Sequence in context: A068823 A264301 A251091 * A253090 A154226 A177187

Adjacent sequences:  A159075 A159076 A159077 * A159079 A159080 A159081

KEYWORD

nonn,base,more

AUTHOR

Johan Särnbratt, Apr 04 2009

EXTENSIONS

a(11) - a(16) from Johan Särnbratt, Apr 21 2009

STATUS

approved

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Last modified September 22 22:24 EDT 2020. Contains 337291 sequences. (Running on oeis4.)