login
A331098
The numbers such that the sum of their proper divisors minus the product of their digits equals the number.
2
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
1,1
COMMENTS
The perfect numbers containing a 0 digit are all in this sequence.
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..30 (terms < 10^13)
EXAMPLE
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.
MATHEMATICA
Select[Range[10^6], DivisorSigma[1, #] - Times @@ IntegerDigits[#] == 2 # &] (* Amiram Eldar, Jan 18 2020 *)
PROG
(PARI) isok(n) = my(d=digits(n)); sigma(n) - n - vecprod(d) == n; \\ Michel Marcus, Jan 18 2020
CROSSREFS
KEYWORD
nonn,base,less
AUTHOR
Scott R. Shannon, Jan 09 2020
EXTENSIONS
a(13)-a(14) from Michel Marcus, Jan 18 2020
a(15)-a(26) from Giovanni Resta, Jan 18 2020
STATUS
approved