cp's OEIS Frontend

A191221 Numbers k such that k plus the sum of the digits of k is prime, and R(k) plus the sum of the digits of k is prime, where R(k) = A004086(k).

%I A191221 #13 Feb 19 2019 00:34:02
%S A191221 1,10,11,19,35,37,53,59,73,91,95,100,101,143,181,218,232,250,272,296,
%T A191221 298,323,341,343,365,383,385,418,436,454,490,509,527,547,563,583,610,
%U A191221 634,650,656,670,692,725,727,745,749,767,787,812,814,838,850,892,905,947,949,1009
%N A191221 Numbers k such that k plus the sum of the digits of k is prime, and R(k) plus the sum of the digits of k is prime, where R(k) = A004086(k).
%C A191221 Numbers ending with zero(s) when reversed have fewer digits.
%H A191221 Nathaniel Johnston, <a href="/A191221/b191221.txt">Table of n, a(n) for n = 1..10000</a>
%e A191221 143 and 341 belong to the sequence since 143 + (1+4+3) = 151 is prime and 341 + (3+4+1) = 349 is also a prime.
%p A191221 read(transforms): isA191221 := proc(n) local r: r:=digrev(n): return (isprime(n+digsum(n)) and isprime(r+digsum(r))): end: A191221 := proc(n) option remember: local k: if(n=1)then return 1: fi: for k from procname(n-1)+1 do if(isA191221(k))then return k: fi: od: end: seq(A191221(n),n=1..57); # _Nathaniel Johnston_, May 27 2011
%t A191221 nrQ[n_]:=Module[{idn=IntegerDigits[n],t},t=Total[idn];And@@PrimeQ[{n+t, FromDigits[Reverse[idn]]+t}]]; Select[Range[1200],nrQ] (* _Harvey P. Dale_, Feb 24 2013 *)
%Y A191221 Cf. A004086, A007953.
%K A191221 nonn,base,easy
%O A191221 1,2
%A A191221 _Carmine Suriano_, May 27 2011