cp's OEIS Frontend

A092595 Numbers k such that the sum of decimal digits of k and k+1 are both prime numbers, i.e., both k and k+1 are in A028834.

%I A092595 #42 Jan 28 2025 18:56:34
%S A092595 2,11,20,29,49,101,110,119,139,199,200,209,229,289,319,379,409,469,
%T A092595 559,649,739,829,919,1001,1010,1019,1039,1099,1100,1109,1129,1189,
%U A092595 1219,1279,1309,1369,1459,1549,1639,1729,1819,1909,2000,2009,2029,2089,2119,2179
%N A092595 Numbers k such that the sum of decimal digits of k and k+1 are both prime numbers, i.e., both k and k+1 are in A028834.
%C A092595 Interestingly, the following numbers n are such that the sum of the decimal digits of n, n+1, and n+2 are all prime numbers: 199, 1099, 10099, 19999, 100099, 109999, . . . -_Harvey P. Dale_, Jan 28 2025
%H A092595 J.W.L. (Jan) Eerland, <a href="/A092595/b092595.txt">Table of n, a(n) for n = 1..10000.</a>
%e A092595 For k=4429, digitsum(k) = 4 + 4 + 2 + 9 = 19, digitsum(k+1) = 4 + 4 + 3 + 0 = 11.
%t A092595 t=Table[0, {256}]; j=1; Do[s=Apply[Plus, IntegerDigits[n]]; s1=Apply[Plus, IntegerDigits[n+1]]; If[PrimeQ[s]&&PrimeQ[s1], Print[n]; t[[j]]=n; j=j+1], {n, 1, 10000}]; t
%t A092595 DeleteCases[ParallelTable[If[PrimeQ[Total[IntegerDigits[n]]]&&PrimeQ[Total[IntegerDigits[n+1]]],n,a],{n,2,952999}],a] (* _J.W.L. (Jan) Eerland_, Dec 20 2021 *)
%t A092595 SequencePosition[Table[If[PrimeQ[Total[IntegerDigits[n]]],1,0],{n,2500}],{1,1}][[;;,1]] (* _Harvey P. Dale_, Jan 28 2025 *)
%o A092595 (PARI) isok(n) = isprime(sumdigits(n)) && isprime(sumdigits(n+1)); \\ _Michel Marcus_, Jul 29 2017
%Y A092595 Cf. A028834.
%K A092595 base,nonn
%O A092595 1,1
%A A092595 _Labos Elemer_, Mar 17 2004