A277216 -id:A277216 - cp's OEIS frontend

A277217 Numbers k for which the sum of digits of sigma(k) = the product of digits of sigma(k).

1, 2, 3, 4, 5, 7, 86, 126, 131, 206, 207, 311, 1123, 1213, 2113, 4111, 10921, 12211, 16581, 21121, 21211, 22111, 39660, 51558, 52940, 60812, 61504, 63548, 68822, 81303, 83409, 87081, 87451, 89708, 94523, 97307, 106118, 108527, 110387, 111611, 120831, 160271

Offset: 1

Jaroslav Krizek, Oct 05 2016

Numbers k such that A067342(k) = A277216(k).
Prime terms: 2, 3, 5, 7, 131, 311, 1123, 1213, 2113, 4111, 12211, ...
Corresponding values of sigma(a(n)): 1, 3, 4, 7, 6, 8, 132, 312, 132, 312, 312, 312, 1124, 1214, 2114, ...
Only 196 terms less than 35*10^8. - Robert G. Wilson v, Oct 07 2016
Alternatively, numbers k such that sigma(k) is in A034710. - Charlie Neder, Dec 27 2018

			86 is a term because sigma(86) = 132; sum and product of digits of 132 = 6.

Robert G. Wilson v, Table of n, a(n) for n = 1..196 (first 100 terms from Jaroslav Krizek)

Cf. A000203, A007953, A007954, A034710.

Cf. A067342 (sum of decimal digits of sigma(n)), A277216 (product of decimal digits of sigma(n)).

[n: n in [1..100000] | &+Intseq(SumOfDivisors(n)) eq &*Intseq(SumOfDivisors(n))];

Select[Range@ 200000, Total@ # == Times @@ # &@ IntegerDigits@ DivisorSigma[1, #] &] (* Michael De Vlieger, Oct 06 2016 *)

isok(n) = my(d=digits(sigma(n))); vecprod(d) == vecsum(d); \\ Michel Marcus, Mar 02 2019

cp's OEIS Frontend

A277217 Numbers k for which the sum of digits of sigma(k) = the product of digits of sigma(k).

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