A333011 - OEIS

A333011

Integers which can be written in only one way as a sum of two distinct nonzero pentagonal numbers.

6, 13, 17, 23, 27, 34, 36, 40, 47, 52, 56, 57, 63, 71, 73, 75, 82, 86, 92, 93, 97, 104, 105, 114, 118, 121, 122, 127, 129, 139, 143, 146, 150, 152, 157, 162, 167, 168, 177, 180, 181, 187, 188, 196, 198, 209, 222, 227, 232, 237, 245, 246, 248, 252, 259, 261, 262

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OFFSET

1,1

COMMENTS

The first term of A332988 not in this sequence is 211.

LINKS

Jinyuan Wang, Table of n, a(n) for n = 1..10000

PROG

(PARI) is(k) = sum(i=1, sqrt(1+12*k)\6, sqrt(1+24*k+12*i-36*i*i)%6==5) == 1; \\ Jinyuan Wang, Mar 06 2020

CROSSREFS

Cf. A000326, A332988, A333011, A333012, A333013, A333014, A333015.

Sequence in context: A070899 A265756 A332988 * A197562 A322431 A153696

Adjacent sequences: A333008 A333009 A333010 * A333012 A333013 A333014

KEYWORD

nonn

AUTHOR

Olivier Gérard, Mar 05 2020

STATUS

approved