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Pentagonal pyramidal numbers which are the sum of two other such numbers: A002411(k) = A002411(i)+A002411(j) with i,j>0.
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%I #13 Apr 25 2016 11:45:30

%S 37926,279046,2514726,34797726,71254566,348145726,566225926,606245926,

%T 828497488,1206646551,8750871976,11481404326,21078151200,28120290876,

%U 62963640936,75128827176,77009692800,96868002726,120282238710,147061923750,165998399400,297022824126,325443925926,416397477888

%N Pentagonal pyramidal numbers which are the sum of two other such numbers: A002411(k) = A002411(i)+A002411(j) with i,j>0.

%C The corresponding indices are listed in A172437. This answers a question posed in A133459.

%H Donovan Johnson, <a href="/A172425/b172425.txt">Table of n, a(n) for n = 1..160</a>

%F a(n) = A002411(A172437(n))

%o (PARI) for(n=1,99999, for(m=1,n-1, isA002411(A002411(n)-A002411(m)) | next; print1(A002411(n)", "); break)) /* needs A002411() and isA240011() */

%Y Cf. A133459, A172437.

%K nonn

%O 1,1

%A _M. F. Hasler_, Nov 20 2010