A063137 Composite numbers not divisible by 2, 3 or 5 which contain their largest prime factor as a substring in base 2.

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

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 A373526

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