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A284921 Numbers with digits 2 and 7 only. 5
2, 7, 22, 27, 72, 77, 222, 227, 272, 277, 722, 727, 772, 777, 2222, 2227, 2272, 2277, 2722, 2727, 2772, 2777, 7222, 7227, 7272, 7277, 7722, 7727, 7772, 7777, 22222, 22227, 22272, 22277, 22722, 22727, 22772, 22777, 27222, 27227, 27272, 27277, 27722, 27727 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Prime terms are in A020459.

LINKS

Table of n, a(n) for n=1..44.

MATHEMATICA

Flatten@ Array[FromDigits /@ Tuples[{2, 7}, #] &, 5] (* Michael De Vlieger, Apr 06 2017 *)

PROG

(MAGMA) [n: n in [1..100000] | Set(IntegerToSequence(n, 10)) subset {2, 7}]

CROSSREFS

Cf. Numbers with digits 2 and k only for k = 0 - 1 and 3 - 9: A169965 (k = 0), A007931 (k = 1), A032810 (k = 3), A284920 (k = 4), A072961 (k = 5), A284632 (k = 6), this sequence (k = 7), A284922 (k = 8), A284923 (k = 9).

Sequence in context: A229493 A175871 A137107 * A174236 A131856 A283236

Adjacent sequences:  A284918 A284919 A284920 * A284922 A284923 A284924

KEYWORD

nonn,base

AUTHOR

Jaroslav Krizek, Apr 05 2017

STATUS

approved

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Last modified August 8 14:36 EDT 2020. Contains 336298 sequences. (Running on oeis4.)