login
Sum of composite numbers between prime p and nextprime(p) is palindromic.
5

%I #19 Aug 11 2024 14:41:32

%S 3,5,109,193,281,509,661,827,857,1439,2111,3433,3889,3967,4549,6661,

%T 7001,8467,10099,17203,18583,21011,21611,23831,24847,25117,26261,

%U 26497,26861,28181,29587,30497,31307,47569,47869,49789,53939,54139,66361

%N Sum of composite numbers between prime p and nextprime(p) is palindromic.

%H Chai Wah Wu, <a href="/A054266/b054266.txt">Table of n, a(n) for n = 1..10000</a> (n = 1..500 from Zak Seidov)

%H P. De Geest, <a href="https://www.worldofnumbers.com/index.html">World!Of Numbers</a>

%e a(4)=193 since between 193 and next prime 197 we get the palindromic sum 194 + 195 + 196 = 585.

%t okQ[l_]:=Module[{x=IntegerDigits[Total[Range[First[l]+1, Last[l]-1]]]},x==Reverse[x]];Transpose[Select[Partition[ Prime[Range[2,6700]],2,1],okQ]][[1]] (* _Harvey P. Dale_, Mar 18 2011 *)

%Y Cf. A046933, A054264, A054265, A054267, A054268.

%K nonn,base

%O 1,1

%A _Patrick De Geest_, Apr 15 2000

%E Corrected and extended b-file by _Chai Wah Wu_, Feb 25 2018