A331098 The numbers such that the sum of their proper divisors minus the product of their digits equals the number.
198, 4172, 7144, 27824, 72212, 111126, 1111134, 1113114, 1131114, 7121212, 11131122, 13111122, 33550336, 111711124, 1111113114, 1111212172, 1113111114, 2111211172, 7111211212, 8589869056, 11112117212, 11113111122, 11121121172, 11711121212, 13111111122, 17112111212
Offset: 1
Examples
198 is a term: A001065(198) = 270, A007954(198) = 72, and 270 - 72 - 198. 4172 is a term: A001065(4172) = 4228, A007954(4172) = 56, and 4228 - 56 = 4172.
Links
- Giovanni Resta, Table of n, a(n) for n = 1..30 (terms < 10^13)
Programs
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Mathematica
Select[Range[10^6], DivisorSigma[1, #] - Times @@ IntegerDigits[#] == 2 # &] (* Amiram Eldar, Jan 18 2020 *)
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PARI
isok(n) = my(d=digits(n)); sigma(n) - n - vecprod(d) == n; \\ Michel Marcus, Jan 18 2020
Extensions
a(13)-a(14) from Michel Marcus, Jan 18 2020
a(15)-a(26) from Giovanni Resta, Jan 18 2020
Comments