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A270540 Numbers that are equal to the number of their digits multiplied by the sum of the fifth powers of the digits. 0
0, 1, 1232, 4100, 268542 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
Terms up to 10^8.
No further terms after 10^7 since 10^k > k^2*9^5 beyond that point. - Ray Chandler, Apr 01 2016
LINKS
EXAMPLE
4100 is a term because 4100 = 4*(4^5+1^5+0^5+0^5).
MATHEMATICA
Position[ Table[ IntegerLength[ k] Sum[( Floor[k/10^n] - 10 Floor[k/10^(n + 1)])^5, {n, 0, IntegerLength@ k}] - k, {k, 1, 10^6}], 0] // Flatten = {1, 1232, 4100, 268542}
Select[Range[10^7], With[{id=IntegerDigits[#]}, #==Length[id]*Plus@@(id^5)]&] (* Ray Chandler, Apr 01 2016 *)
PROG
(PARI) isok(n) = my(d=digits(n)); n == #d*sum(k=1, #d, d[k]^5); \\ Michel Marcus, Mar 25 2016
CROSSREFS
Cf. A055014.
Sequence in context: A278018 A182721 A183881 * A206272 A064942 A101311
KEYWORD
nonn,base,fini,full
AUTHOR
EXTENSIONS
a(5) from Michel Marcus, Mar 25 2016
STATUS
approved

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Last modified June 18 00:47 EDT 2024. Contains 373468 sequences. (Running on oeis4.)