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Search: id:A135051
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| A135051 |
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Pyramid game person numbers that have integer solutions for: Solve[m(m + 1)/2 + 1 - n == 0, m]. |
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+0
1
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| 7, 79, 191, 407, 631, 991, 1327, 1831, 2279, 2927, 3487, 4279, 4951, 5887, 6671, 7751, 8647, 9871
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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This result comes from looking for "perfect Pyramids":
Solve[m(m + 1)/2 + 1 - n == 0, m]
f[n_] = (1/2) (-1+ Sqrt[ -7 + 8 n])
Integer solutions have the form such that:
IntegerQ[2*Sqrt[ -7 + 8*n]] && Mod[n - 7, 8] == 0
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FORMULA
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a(n) = If[ IntegerQ[2*Sqrt[ -7 + 8*n]] && Mod[n - 7, 8] == 0, n]
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MATHEMATICA
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Flatten[Table[If[ IntegerQ[2*Sqrt[ -7 + 8*n]] && Mod[n - 7, 8] == 0, n, {}], {n, 1, 10000}]]
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CROSSREFS
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Sequence in context: A140613 A139945 A023285 this_sequence A014232 A154592 A075896
Adjacent sequences: A135048 A135049 A135050 this_sequence A135052 A135053 A135054
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KEYWORD
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nonn,uned
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AUTHOR
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Roger Bagula (rlbagulatftn(AT)yahoo.com), Jan 31 2008
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