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.

A029772 Every digit that appears in k also appears at least once in k^2.

Original entry on oeis.org

0, 1, 5, 6, 10, 11, 25, 27, 50, 55, 60, 63, 64, 66, 74, 76, 95, 96, 99, 100, 101, 105, 110, 111, 112, 115, 116, 125, 139, 142, 199, 205, 211, 222, 225, 232, 250, 255, 261, 270, 275, 277, 278, 285, 288, 305, 323, 363, 364, 366, 371, 376, 405, 421
Offset: 1

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Keywords

Examples

			55 is in the list because 55^2 = 3025 and 5 appears in 3025.
323 is in the list because 323^2 = 104329 and 2, 3 appear in 104329.
		

Crossrefs

See A046827, where it is required that the digits of n appear in n^2 at least as often as they appear in n.

Programs

  • Magma
    [n: n in [0..500] | Intseq(n) subset Intseq(n^2)]; // Bruno Berselli, Aug 01 2013
    
  • Mathematica
    d[n_]:=IntegerDigits[n]; Select[Range[0,421],Complement[d[#],d[#^2]]=={}&] (* Jayanta Basu, Jun 02 2013 *)
  • Python
    from itertools import count, islice
    def A029772_gen(startvalue=0): # generator of terms >= startvalue
        return filter(lambda n:set(str(n)) <= set(str(n**2)), count(max(startvalue,0)))
    A029772_list = list(islice(A029772_gen(),20)) # Chai Wah Wu, Apr 03 2023