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.

A243819 Composite numbers n such that every divisor of n greater than one contains the digit 0.

Original entry on oeis.org

10201, 10403, 10609, 10807, 11009, 11021, 31007, 40501, 41303, 41309, 42907, 43709, 50803, 51409, 51809, 60701, 61307, 61903, 64307, 65509, 70801, 71609, 72203, 73027, 75007, 76409, 81709, 91607, 97049, 101909, 102313, 102919, 103121, 103927, 104131, 104333, 104339, 104939, 104957, 105163, 105949
Offset: 1

Views

Author

Barbara W. Waddell and Robert G. Wilson v, Jun 11 2014

Keywords

Examples

			The divisors of 10201 are {1, 101, and 10201}. Except for 1 each has a 0 in its decimal expansion.
		

Crossrefs

Programs

  • Mathematica
    fQ[n_, dgt_] := Union[ MemberQ[#, dgt] & /@ IntegerDigits@ Rest@ Divisors@ n][[1]]; Select[ Range[2, 106000], !PrimeQ[#] && fQ[#, 0] &]
    cd0Q[n_]:=CompositeQ[n]&&AllTrue[Rest[Divisors[n]],DigitCount[#,10,0]>0&]; Select[Range[ 106000],cd0Q] (* Harvey P. Dale, Aug 15 2024 *)

Extensions

Definition slightly modified by Harvey P. Dale, Aug 15 2024