A274810 Numbers n such that n and n+1 both have 38 divisors.

9399153082499072, 20164508489351168, 21992587709382656, 25039386409435136, 25537472011436031, 26756191491457023, 45443223518445567, 47474422651813887, 59772891590033408, 64241529683443712, 73381925783601152

Offset: 1

Author

Charles R Greathouse IV, Jul 08 2016

Keywords

• nonn

Links

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

Crossrefs

Intersection of A005237 and A175747.

Programs

PARI

is(n)=numdiv(n)==38 && numdiv(n+1)==38

PARI

has(n)=if(n%4==2, ispower(n/2, 18, &n) && isprime(n), bitand(n, 524287)==262144 && isprime(n>>18) && n>262144) \\ check if n is even with 38 divisors
list(lim)=my(v=List(), t); forprime(p=2, sqrtnint(lim\=1, 37), t=p^37; if(has(t+1), listput(v, t)); if(has(t-1), listput(v, t-1))); forprime(p=3, sqrtnint(lim\3, 18), my(p18=p^18); forprime(q=3, lim\p18, if(p==q, next); t=p18*q; if(has(t+1), listput(v, t)); if(has(t-1), listput(v, t-1)))); Set(v)