cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A331098 The numbers such that the sum of their proper divisors minus the product of their digits equals the number.

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%I A331098 #22 Jan 20 2020 04:23:00
%S A331098 198,4172,7144,27824,72212,111126,1111134,1113114,1131114,7121212,
%T A331098 11131122,13111122,33550336,111711124,1111113114,1111212172,
%U A331098 1113111114,2111211172,7111211212,8589869056,11112117212,11113111122,11121121172,11711121212,13111111122,17112111212
%N A331098 The numbers such that the sum of their proper divisors minus the product of their digits equals the number.
%C A331098 The perfect numbers containing a 0 digit are all in this sequence.
%H A331098 Giovanni Resta, <a href="/A331098/b331098.txt">Table of n, a(n) for n = 1..30</a> (terms < 10^13)
%e A331098 198 is a term: A001065(198) = 270, A007954(198) = 72, and 270 - 72 - 198.
%e A331098 4172 is a term: A001065(4172) = 4228, A007954(4172) = 56, and 4228 - 56 = 4172.
%t A331098 Select[Range[10^6], DivisorSigma[1, #] - Times @@ IntegerDigits[#] == 2 # &] (* _Amiram Eldar_, Jan 18 2020 *)
%o A331098 (PARI) isok(n) = my(d=digits(n)); sigma(n) - n - vecprod(d) == n; \\ _Michel Marcus_, Jan 18 2020
%Y A331098 Cf. A001065, A007954, A331096.
%K A331098 nonn,base,less
%O A331098 1,1
%A A331098 _Scott R. Shannon_, Jan 09 2020
%E A331098 a(13)-a(14) from _Michel Marcus_, Jan 18 2020
%E A331098 a(15)-a(26) from _Giovanni Resta_, Jan 18 2020