A030679 Cube root of A030678.

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

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