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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 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

Table of n, a(n) for n=1..6.

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

Cf. A059461, A059462, A059463, A059464, A059465, A059466, A059467, A059468.

Sequence in context: A002606 A047637 A286440 * A347203 A176089 A261112

Adjacent sequences:  A271445 A271446 A271447 * A271449 A271450 A271451

KEYWORD

nonn,base,less,more

AUTHOR

Giovanni Resta, May 02 2016

STATUS

approved

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Last modified December 9 06:07 EST 2021. Contains 349627 sequences. (Running on oeis4.)