login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A181881 The sums of pairs of adjacent terms are the odd palindromic primes in ascending order. 4

%I #41 Jan 02 2023 12:30:47

%S 1,2,3,4,7,94,37,114,67,124,189,164,209,174,553,204,583,214,705,224,

%T 10077,424,10177,1134,10277,2144,10577,2244,11087,2744,11187,3154,

%U 11587,3864,11687,4374,11987,4574,12087,5384,12587,5594,12887,6504,13387

%N The sums of pairs of adjacent terms are the odd palindromic primes in ascending order.

%C This sequence was originally presented at http://www.sanaristikot.net by Jaakko Himberg (jaska.himberg(AT)suomiforum.com), Nov 06 2010. [Added by _V.J. Pohjola_, Nov 25 2010.]

%C There are four possible solutions: see A181881-A181884.

%H V. J. Pohjola, <a href="/A181881/b181881.txt">Table of n, a(n) for n = 1..113</a>

%H V. J. Pohjola, <a href="http://list.seqfan.eu/oldermail/seqfan/2010-November/006331.html">a(n)+a(n+1) = palindromic prime</a>, Posting to the Sequence Fans Mailing List, Nov 11 2010.

%t lst = {}; a = 1; c = 1; Label[alku1]; b = c; Label[alku2]; b =b + 1; If[PrimeQ[a + b] && IntegerDigits[a + b] == Reverse[IntegerDigits[a + b]], AppendTo[lst, a], Goto[alku2]]; c = a; a = b; If[a < 100000, Goto[alku1]]; lst (* _V.J. Pohjola_, Nov 22 2010 *)

%t a[1] = 1; pp = Select[Prime[Range[3000]], PalindromeQ]; lp = Length[pp]-1; aa = Table[a[n] + a[n+1], {n, lp}]; Array[a, lp] /. Solve[Thread[aa == Rest[pp]]][[1]] (* _Jean-François Alcover_, Feb 17 2018 *)

%Y Cf. A002385, A181882, A181883, A181884.

%K nonn,easy,base

%O 1,2

%A _N. J. A. Sloane_, Nov 18 2010

%E More terms from _V.J. Pohjola_, Nov 22 2010

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified April 19 12:14 EDT 2024. Contains 371792 sequences. (Running on oeis4.)