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A271448 Numbers which are the sum of their proper divisors containing the digit 2. 8
546, 39312, 60168, 534688, 2281353180, 272240989636 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
COMMENTS
a(7) > 10^12.
For each digit d=0..9 there is a corresponding sequence in the OEIS (see Crossrefs), except for d=1, because up to 10^12, only 2654635632 is equal to the sum of its proper divisors which contain the digit 1.
LINKS
EXAMPLE
The proper divisors of 546 are 1, 2, 3, 6, 7, 13, 14, 21, 26, 39, 42, 78, 91, 182, and 273. Since 2+21+26+42+182+273 = 546, 546 is a term.
MATHEMATICA
Select[Range[10^6], # == Plus @@ Select[Most@ Divisors@#, MemberQ[ IntegerDigits@ #, 2] &] &]
CROSSREFS
Sequence in context: A002606 A047637 A286440 * A347203 A176089 A261112
KEYWORD
nonn,base,less,more
AUTHOR
Giovanni Resta, May 02 2016
STATUS
approved

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Last modified March 29 10:59 EDT 2024. Contains 371277 sequences. (Running on oeis4.)