A273460 - OEIS

A273460

Numbers n such that sum of the divisors of n (except 1 and n) is equal to the product of the digits of n.

98, 101, 103, 107, 109, 307, 329, 401, 409, 503, 509, 601, 607, 701, 709, 809, 907, 1009, 1013, 1019, 1021, 1031, 1033, 1039, 1049, 1051, 1061, 1063, 1069, 1087, 1091, 1093, 1097, 1103, 1109, 1201, 1301, 1303, 1307, 1409, 1601, 1607, 1609, 1709, 1801, 1901

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

Or numbers n such that A048050(n) = A007954(n).

Most of the terms are primes which have at least one 0 among their digits (A056709). The composite numbers of the sequence are 98, 329, 3383, 4343, 5561, 6623, 12773, 17267, 21479, 57721, 129383, 136259, 142943, 172793, 246959, 256631, 292571,...

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000

EXAMPLE

sigma(98) - 98 - 1 = 171 - 98 - 1 = 72 and 8*9 = 72 so 98 is in the sequence.

MAPLE

with(numtheory):

for n from 1 to 3000 do:

q:=convert(n, base, 10):n0:=nops(q):

pr:=product('q[i]', 'i'=1..n0):p:=sigma(n)-n-1:

if p=pr

then

printf(`%d, `, n):