A030668 -id:A030668 - cp's OEIS frontend

A030669 Cube root of A030668.

5, 3, 7, 16, 8, 4, 9, 20, 21, 10, 48, 5, 11, 52, 25, 55, 12, 57, 27, 59, 6, 61, 62, 29, 63, 64, 14, 66, 31, 67, 68, 32, 15, 7, 33, 154, 72, 73, 34, 16, 161, 35, 76, 164, 77, 36, 78, 169, 17, 37, 8, 174, 81, 38, 82, 178, 83, 18, 39, 182, 85, 184, 86, 40, 87, 188

Offset: 1

Patrick De Geest

a(n) = A018852(n) if n is not a cube. - Robert Israel, Dec 25 2018

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

Cf. A018852, A030668.

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:
map(f, [$1..100]); # Robert Israel, Dec 25 2018

A030678 Smallest nontrivial extension of n-th palindrome which is a cube.

Original entry on oeis.org

125, 27, 343, 4096, 512, 64, 729, 8000, 9261, 110592, 226981, 3375, 4410944, 551368, 6644672, 778688, 884736, 9938375, 101194696, 111284641, 12167, 13144256, 14172488, 151419437, 16194277, 17173512, 1815848, 191102976

Offset: 1

Patrick De Geest

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

Cf. A002113, A030668, A030679.

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^3 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

a(n) = A030668(A002113(n+1)) = A030679(n)^3. - Robert Israel, Dec 25 2018

cp's OEIS Frontend

A030669 Cube root of A030668.

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