cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A030160 Cubes in which parity of digits alternates.

Original entry on oeis.org

0, 1, 8, 27, 125, 216, 343, 729, 5832, 12167, 614125, 658503, 1030301, 1092727, 4741632, 8741816, 27270901, 27818127, 47832147, 381078125, 4767078987, 14905098181, 21670967872, 496981290961, 874545616547, 903670125632
Offset: 1

Views

Author

Patrick De Geest

Keywords

Comments

The number ((1+10^2)*(1+10^8)*(1+10^32)*(1+10^128)*(1+10^512))^3 is a term of the sequence. - Giovanni Resta, Aug 16 2018

Links

Crossrefs

Cf. A030159, A030161, A030162, A030152.

Programs

  • Mathematica
    altQ[n_] := n < 10 || Union[Total /@ Partition[ Mod[ IntegerDigits@n, 2], 2, 1]] == {1}; Select[ Range[0, 10^4]^3, altQ[#] &] (* Giovanni Resta, Aug 16 2018 *)

Extensions

Offset changed by Giovanni Resta, Aug 16 2018

A030159 Numbers n such that in n^3 the parity of digits alternates.

Original entry on oeis.org

0, 1, 2, 3, 5, 6, 7, 9, 18, 23, 85, 87, 101, 103, 168, 206, 301, 303, 363, 725, 1683, 2461, 2788, 7921, 9563, 9668, 20606, 28443, 29501, 45168, 46701, 49501, 63556, 78206, 80901, 90009, 167861, 168069, 208288, 278636, 331841, 375121, 440468
Offset: 1

Views

Author

Patrick De Geest

Keywords

Comments

A simple heuristic argument suggests that this sequence (albeit rather sparse) is infinite. The numbers of terms of k digits, for k=1..14, are 8, 4, 8, 6, 10, 14, 20, 18, 33, 23, 42, 37, 46, 77, respectively. The 5 numbers obtained multiplying the first h=1..5 terms of (1+10^2, 1+10^8, 1+10^32, 1+10^128, 1+10^512), are all member of the sequence. The largest one is a number of 683 digits whose alternating cube has 2047 digits. - Giovanni Resta, Aug 16 2018

Links

Crossrefs

Cf. A030160, A030161, A030162, A030151.

Programs

  • Mathematica
    n3pdaQ[n_]:=Module[{pty=Boole[EvenQ/@IntegerDigits[n^3]],len= IntegerLength[ n^3]}, pty== PadRight[{},len,{1,0}]||pty==PadRight[ {}, len, {0,1}]]; Join[{0},Select[Range[450000],n3pdaQ]] (* Harvey P. Dale, Mar 26 2018 *)

A030161 Numbers k such that in k and k^3 the parity of digits alternates.

Original entry on oeis.org

0, 1, 2, 3, 5, 6, 7, 9, 18, 23, 85, 87, 101, 103, 301, 303, 363, 725
Offset: 1

Views

Author

Patrick De Geest

Keywords

Comments

No other values of k < 2100000. - Larry Reeves (larryr(AT)acm.org), Sep 25 2000

Crossrefs

Cf. A030162.
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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