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A063137 Composite numbers not divisible by 2, 3 or 5 which contain their largest prime factor as a substring in base 2. 1
91, 343, 407, 493, 539, 637, 893, 1001, 1189, 1309, 1343, 1403, 1643, 1681, 1771, 1859, 1961, 2527, 2717, 2783, 3059, 3151, 3179, 3223, 3451, 3703, 3731, 3773, 3887, 4063, 4199, 4459, 4579, 4669, 4823, 4913, 4991, 5291, 5453, 5491, 5719 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

EXAMPLE

a(7)= 19 * 47= 893: '1101111101' contains '101111' (47) and 5 < 19.

PROG

(PARI) sub(a, b)=my(m=1<<(log(2*a+1)\log(2))-1); while(b>=a, if(bitand(b, m)==a, return(1)); b>>=1); 0

gpf(n)=n=factor(n)[, 1]; n[#n]

is(n)=gcd(n, 30)==1&&!isprime(n)&&sub(gpf(n), n) \\ Charles R Greathouse IV, Dec 08 2011

CROSSREFS

Cf. A062238.

Sequence in context: A020441 A209255 A273799 * A234131 A234124 A180942

Adjacent sequences:  A063134 A063135 A063136 * A063138 A063139 A063140

KEYWORD

base,nonn

AUTHOR

Robert G. Wilson v, Aug 08 2001

EXTENSIONS

Edited by Frank Ellermann, Feb 08 2002

STATUS

approved

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Last modified November 20 17:09 EST 2019. Contains 329337 sequences. (Running on oeis4.)