A185300 Numbers k such that (sum of the decimal digits of k) + (product of the decimal digits of k) is prime.

1, 11, 12, 13, 15, 16, 18, 19, 20, 21, 23, 25, 27, 29, 30, 31, 32, 34, 35, 37, 43, 45, 50, 51, 52, 53, 54, 56, 57, 58, 59, 61, 65, 70, 72, 73, 75, 78, 79, 81, 85, 87, 89, 91, 92, 95, 97, 98, 101, 102, 104, 106, 110, 120, 140, 160, 200, 201, 203, 205, 209, 210, 223, 225, 230, 232

Offset

1,2

Links

Robert Israel, Table of n, a(n) for n = 1..10000

Example

236 is in the sequence because 2 + 3 + 6 + 2*3*6 = 11 + 36 = 47 is prime.

Maple

A007953 := proc(n) add(d, d=convert(n, base, 10)) ; end proc:
A007954 := proc(n) mul(d, d=convert(n, base, 10)) ; end proc:
isA185300 := proc(n) isprime(A007953(n)+A007954(n)) ; end proc:
for n from 1 to 300 do if isA185300(n) then printf("%a, ", n) ; end if; end do: # R. J. Mathar, Feb 08 2011

Prog

(Magma) [n: n in [1..232] | IsPrime(&+Intseq(n)+&*Intseq(n))]; // Bruno Berselli, Aug 02 2012
(PARI) is(n)=my(d=digits(n)); isprime(vecsum(d)+vecprod(d)) \\ Charles R Greathouse IV, Jun 06 2017

Crossrefs

Cf. A007953, A007954.

Sequence in context: A138595 A192271 A214423 * A097932 A031300 A111019

Adjacent sequences: A185297 A185298 A185299 * A185301 A185302 A185303

Keyword

nonn,base,easy

Author

Michel Lagneau, Feb 03 2011

Status

approved