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A030679 Cube root of A030678. 2
5, 3, 7, 16, 8, 4, 9, 20, 21, 48, 61, 15, 164, 82, 188, 92, 96, 215, 466, 481, 23, 236, 242, 533, 253, 258, 122, 576, 587, 277, 606, 615, 624, 632, 64, 301, 656, 143, 312, 679, 1479, 322, 70, 707, 714, 72, 1565, 34, 1593, 346, 1619, 1632, 763, 357, 1668 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Robert Israel, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = A030669(A002113(n+1)) = A030678(n)^(1/3). - Robert Israel, Dec 25 2018

MAPLE

N:= 3: # to get extensions of all palindromes of <= N digits

f:= proc(n) local d, x;

  for d from 1 do

    x:= ceil((n*10^d)^(1/3));

    if x^3 < (n+1)*10^d then return x fi

  od

end proc:

digrev:= proc(n) local i, L;

  L:= convert(n, base, 10);

  add(L[-i]*10^(i-1), i=1..nops(L))

end proc:

Res:= seq(f(i), i=1..9):

for d from 2 to N do

if d::even then

    m:= d/2;

    Res:= Res, seq(f(n*10^m + digrev(n)), n=10^(m-1)..10^m-1);

else

    m:= (d-1)/2;

    Res:= Res, seq(seq(f(n*10^(m+1)+y*10^m+digrev(n)), y=0..9), n=10^(m-1)..10^m-1)

fi

od: Res; # Robert Israel, Dec 25 2018

CROSSREFS

Cf. A002113, A030669, A030678.

Sequence in context: A222598 A221470 A030669 * A077891 A129735 A300502

Adjacent sequences:  A030676 A030677 A030678 * A030680 A030681 A030682

KEYWORD

nonn,base

AUTHOR

Patrick De Geest

STATUS

approved

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Last modified December 6 04:52 EST 2021. Contains 349562 sequences. (Running on oeis4.)