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A206025
Triangular numbers k whose divisors can be partitioned into three disjoint sets whose sums are all sigma(k)/3.
1
120, 780, 2016, 3240, 4560, 5460, 7140, 7260, 9180, 10296, 10440, 12720, 19110, 21528, 23220, 26796, 28680, 28920, 32640, 34980, 37128, 39060, 41328, 49770, 51360, 56280, 61776, 64620, 64980, 73920, 79800, 97020, 100128, 103740, 107880, 114960, 115440, 122760
OFFSET
1,1
COMMENTS
Divisors of triangular number k = 120 can be partitioned into three disjoint sets whose sums are all sigma(k)/3 and this value is triangular numbers (=120). Are there other such triangular numbers?
LINKS
EXAMPLE
Triangular number 780 is in sequence because sigma(780)/3 = 784 = 4+780 = 2+5+6+10+12+13+15+20+26+30+39+52+60+65+78+156+195 = 1+3+130+260+390 (summands are all divisors of 780).
CROSSREFS
Intersection of A000217 and A204830.
Subsequence of A023197.
Cf. A000203.
Sequence in context: A052766 A052627 A251264 * A235551 A300664 A029573
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Feb 03 2012
STATUS
approved