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A333014 Numbers which can written in exactly four ways as a sum of two distinct nonzero pentagonal numbers. 4
13352, 18877, 45397, 49052, 52027, 53727, 62652, 64182, 73152, 74977, 76677, 79327, 80671, 85177, 87972, 88577, 90702, 91652, 93302, 96669, 98827, 101752, 106036, 106822, 109227, 109487, 116117, 118477, 125347, 133267, 135786, 138087, 138802, 140852, 141532, 144747, 145302, 145641, 147274, 148077, 148927 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
13352 = P(52) + P(79) = P(29) + P(90) = P(17) + P(93) = P(10) + P(94), where P(n) is the n-th pentagonal number A000326.
PROG
(PARI) is(k) = sum(i=1, sqrt(1+12*k)\6, sqrt(1+24*k+12*i-36*i*i)%6==5) == 4; \\ Jinyuan Wang, Mar 06 2020
CROSSREFS
Sequence in context: A162423 A176465 A185503 * A205196 A235297 A252240
KEYWORD
nonn
AUTHOR
Olivier Gérard, Mar 05 2020
STATUS
approved

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Last modified July 21 01:14 EDT 2024. Contains 374462 sequences. (Running on oeis4.)