A260465 a(n) is the smallest number not already in the sequence such that a(n)^3 begins with n.

1, 3, 7, 16, 8, 4, 9, 2, 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, 70, 33, 154, 72, 73, 34, 74, 161, 35, 76, 164, 77, 36, 78, 169, 17, 37, 80, 174, 81, 38, 82, 178, 83, 18, 39, 182, 85, 184, 86, 40, 87, 188, 189, 19, 191, 89, 193, 90, 194, 42, 91, 197, 92, 199, 43

Offset

1,2

Comments

Conjectured to be a permutation of the natural numbers.

Links

Derek Orr, Table of n, a(n) for n = 1..10000

Formula

a(n) >= n^(1/3) for all n > 0. If a(n) = n^(1/3), then n is a cube. Note the converse is false: a(27) = 14.

Prog

(PARI) v=[]; k=1; while(#v<100, d=digits(k^3); D=digits(#v+1); if(#D<=#d, c=1; for(i=1, #D, if(D[i]!=d[i], c=0; break)); if(c&&!vecsearch(vecsort(v), k), v=concat(v, k); k=0)); k++); v

Crossrefs

Cf. A018852.

Sequence in context: A180503 A153578 A018852 * A060092 A035283 A184863

Adjacent sequences: A260462 A260463 A260464 * A260466 A260467 A260468

Keyword

nonn,base

Author

Derek Orr, Jul 26 2015

Status

approved