A172425 Pentagonal pyramidal numbers which are the sum of two other such numbers: A002411(k) = A002411(i)+A002411(j) with i,j>0.

37926, 279046, 2514726, 34797726, 71254566, 348145726, 566225926, 606245926, 828497488, 1206646551, 8750871976, 11481404326, 21078151200, 28120290876, 62963640936, 75128827176, 77009692800, 96868002726, 120282238710, 147061923750, 165998399400, 297022824126, 325443925926, 416397477888

Offset: 1

Author

M. F. Hasler, Nov 20 2010

Keywords

• nonn

Comments

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

Links

• Donovan Johnson, Table of n, a(n) for n = 1..160

Crossrefs

Cf. A133459, A172437.

Programs

PARI

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

Formula

a(n) = A002411(A172437(n))