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

Author

Patrick De Geest

Keywords

• nonn
• base

Links

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

Crossrefs

Cf. A002113, A030669, A030678.

Programs

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

Formula

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