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A026478
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a(n) = least positive integer > a(n-1) and not of form a(i)*a(j)*a(k) for 1<=i<=j<=k<n.
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0
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1, 2, 3, 5, 7, 11, 13, 16, 17, 19, 23, 24, 29, 31, 36, 37, 40, 41, 43, 47, 53, 54, 56, 59, 60, 61, 67, 71, 73, 79, 81, 83, 84, 88, 89, 90, 97, 100, 101, 103, 104, 107, 109, 113, 126, 127, 128, 131, 132, 135, 136, 137, 139, 140, 149, 150, 151, 152, 156, 157, 163, 167
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| Number of repeated prime divisors of n is a square. - Jason Earls (zevi_35711(AT)yahoo.com), Jul 01 2001
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FORMULA
| 1 together with numbers with 3m+1 prime factors (for some m >= 0).
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PROG
| (PARI) v=[]; for(n=1, 150, v=concat(v, if(issquare(bigomega(n)), n))); v (ignore the zeros)
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CROSSREFS
| Cf. A016777 and A001222.
Sequence in context: A117093 A062063 A167175 * A154893 A084111 A171474
Adjacent sequences: A026475 A026476 A026477 * A026479 A026480 A026481
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KEYWORD
| nonn,easy
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AUTHOR
| Clark Kimberling (ck6(AT)evansville.edu)
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EXTENSIONS
| Formula from Henry Bottomley (se16(AT)btinternet.com), Feb 09 2000. Definition corrected by and more terms from Larry Reeves (larryr(AT)acm.org), Mar 24 2000.
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