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Search: id:A039596
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| A039596 |
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Numbers that are simultaneously triangular and square pyramidal. |
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+0
4
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OFFSET
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1,2
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COMMENT
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Equivalent to 1^2+2^2+3^2+...+r^2 = 1+2+3+...+s = n for some r and s.
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REFERENCES
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D. Wells, Curious and interesting numbers, Penguin Books, p. 108
Joe Roberts, Lure of the Integers, page 245 (entry for 645).
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EXAMPLE
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1^2+2^2+3^2+4^2+5^2 = 1+2+3+...+10 = 55, so 55 is in the sequence.
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CROSSREFS
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Cf. A000330.
Sequence in context: A063873 A063131 A128880 this_sequence A115377 A044144 A044525
Adjacent sequences: A039593 A039594 A039595 this_sequence A039597 A039598 A039599
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KEYWORD
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fini,nonn,full
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AUTHOR
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Felice Russo (felice.russo(AT)katamail.com)
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EXTENSIONS
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Additional comments from Jud McCranie (j.mccranie(AT)comcast.net), Mar 19 2000
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