Year-end appeal: Please make a donation to the OEIS Foundation to support ongoing development and maintenance of the OEIS. We are now in our 61st year, we have over 378,000 sequences, and we’ve reached 11,000 citations (which often say “discovered thanks to the OEIS”).
%I #7 Mar 31 2012 10:26:44
%S 11,112,293,18474,1026475,2207286,4088167,5970048,106081049,206969050,
%T 315070851,425181862,536191973,647373084,766191895,946292976,
%U 1127404157,1309292338,1497303219,1686192100,11694372101,21776190102
%N Partial sum of tetradic primes (A068188).
%C Tetradic primes are primes that are palindromes and use only the digits 0, 1 and 8, so they read the same backwards and upside down. a(1) = 11, a(3) = 293 and a(21) = 11694372101 are primes.
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/TetradicNumber.html">Tetradic Number</a>.
%F a(n) = SUM[i=1..n] A068188(i). a(n) = SUM[i=1..n] {A006072(k) such that A006072(k) is in A000040}.
%e a(21) = 11 + 101 + 181 + 18181 + 1008001 + 1180811 + 1880881 + 1881881 + 100111001 + 100888001 + 108101801 + 110111011 + 111010111 + 111181111 + 118818811 + 180101081 + 181111181 + 181888181 + 188010881 + 188888881 + 10008180001 = 11694372101.
%Y Cf. A000040, A006072, A068188.
%K base,easy,nonn,less
%O 1,1
%A _Jonathan Vos Post_, Jun 16 2006
%E Corrected by _Jens Kruse Andersen_, Apr 27 2010