A274363 Numbers n such that n and n+1 both have 26 divisors.

689278976, 38492803071, 100821266432, 147331919871, 421606494207, 560920563711, 732088143872, 753855967232, 918212890624, 1218308829183, 1414219239423, 1485254832128, 1544826179583, 1566594002943, 1671079555071, 1675433119743, 1681165242368

Offset

1,1

Links

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

Prog

(PARI) is(n)=numdiv(n)==26 && numdiv(n+1)==26
(PARI) has(n)=if(n%4==2, ispower(n/2, 12, &n) && isprime(n), bitand(n, 8191)==4096 && isprime(n>>12) && n>8192) \\ check if n is even with 26 divisors
list(lim)=my(v=List(), t); forprime(p=2, sqrtnint(lim\=1, 25), t=p^25; if(has(t+1), listput(v, t)); if(has(t-1), listput(v, t-1))); forprime(p=3, sqrtnint(lim\3, 12), my(p12=p^12); forprime(q=3, lim\p12, if(p==q, next); t=p12*q; if(has(t+1), listput(v, t)); if(has(t-1), listput(v, t-1)))); Set(v)

Crossrefs

Intersection of A005237 and A137489.

Sequence in context: A172604 A172709 A250434 * A034651 A274813 A203933

Adjacent sequences: A274360 A274361 A274362 * A274364 A274365 A274366

Keyword

nonn

Author

Charles R Greathouse IV, Jun 19 2016

Status

approved