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A090428 Numbers that are k-gons for two or more k's, where k = 3, 4, 5, ..., 16. 4
1, 6, 9, 10, 12, 15, 16, 21, 28, 36, 45, 55, 64, 66, 70, 81, 91, 105, 120, 145, 153, 171, 176, 190, 196, 210, 225, 231, 276, 280, 325, 378, 400, 435, 441, 477, 496, 540, 561, 595, 616, 630, 651, 703, 715, 780, 833, 861, 936, 946, 1035, 1089, 1105, 1128, 1216 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
Eric Weisstein's World of Mathematics, Polygonal Number.
PROG
(PARI) is(n, c=2)=for(s=3, 16, ispolygonal(n, s)&&!c--&&return(s)) \\ M. F. Hasler, Jan 19 2017
CROSSREFS
Sequence in context: A085275 A177201 A090466 * A039725 A262362 A125494
KEYWORD
nonn
AUTHOR
Eric W. Weisstein, Nov 30 2003
STATUS
approved

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Last modified May 29 22:36 EDT 2024. Contains 372954 sequences. (Running on oeis4.)