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A364960
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Numbers k such that A005940(k) is either k itself or its descendant in Doudna-tree, A005940.
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3
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1, 2, 3, 4, 5, 6, 8, 10, 12, 16, 20, 24, 25, 32, 40, 45, 48, 49, 64, 80, 96, 128, 160, 192, 256, 320, 384, 512, 640, 768, 1024, 1280, 1536, 2048, 2560, 3072, 4096, 5120, 6144, 8192, 10240, 12288, 16384, 20480, 24576, 32768, 40131, 40960, 49152, 50575, 65536, 79625, 81920, 98304, 131072, 163840, 196608, 262144, 327680
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OFFSET
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1,2
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COMMENTS
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LINKS
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PROG
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(PARI)
A005940(n) = { my(p=2, t=1); n--; until(!n\=2, if((n%2), (t*=p), p=nextprime(p+1))); (t); };
A064989(n) = {my(f); f = factor(n); if((n>1 && f[1, 1]==2), f[1, 2] = 0); for (i=1, #f~, f[i, 1] = precprime(f[i, 1]-1)); factorback(f)};
isA364960(n) = { my(k=A005940(n)); while(k>n, k = A252463(k)); (k==n); };
(PARI)
Abincompreflen(n, m) = { my(x=binary(n), y=binary(m), u=min(#x, #y)); for(i=1, u, if(x[i]!=y[i], return(i-1))); (u); };
A156552(n) = {my(f = factor(n), p, p2 = 1, res = 0); for(i = 1, #f~, p = 1 << (primepi(f[i, 1]) - 1); res += (p * p2 * (2^(f[i, 2]) - 1)); p2 <<= f[i, 2]); res}; \\ From A156552
A061395(n) = if(n>1, primepi(vecmax(factor(n)[, 1])), 0);
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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