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A375573
Numbers occurring at least three times in Bernoulli's triangle A008949.
3
1, 16, 64, 232, 256, 466, 562, 1024, 1486, 2048, 4096, 15226, 16384, 44552, 65536, 262144, 1048576, 4194304, 16777216, 67108864, 268435456, 1073741824, 4294967296, 17179869184, 68719476736, 274877906944, 1099511627776, 4398046511104, 17592186044416, 70368744177664
OFFSET
1,2
COMMENTS
Equivalently, 1 together with numbers occurring at least three times in columns k >= 1 of Bernoulli's triangle.
Equivalently, 1 together with numbers occurring at least twice in columns k >= 2 of Bernoulli's triangle.
4^j is a term if j >= 0 and j != 1, because 4^j = A008949(2*j,2*j) = A008949(2*j+1,j) = A008949(4^j-1,1) for j >= 2 and A008949(i,0) = 1 for all i. Are 232, 466, 562, 1486, 2048, 15226, 44552 the only terms not of this form? There are no more such terms below 2^70.
Are 1 and 4096 = A008949(12,12) = A008949(13,6) = A008949(90,2) = A008949(4095,1) the only numbers that occur at least 4 times? There are no more such numbers below 2^70.
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved