login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A063964 Numbers n such that n and n+1 have the same sum of squarefree divisors, or sqf(n)=sqf(n+1), where sqf(n) = A048250(n). 1
11, 14, 224, 957, 1334, 1634, 2685, 9347, 13915, 16260, 20145, 20335, 33998, 37236, 42251, 42818, 51624, 55308, 56419, 56975, 71874, 74918, 77748, 79824, 79826, 79833, 84134, 93632, 106600, 111506, 120680, 122073, 138237, 142116, 147454 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harry J. Smith, Table of n, a(n) for n=1,...,170

PROG

(PARI) sqf(n) = sumdiv(n, d, if(issquarefree(d), d, 0)); for(n=1, 10^7, if(sqf(n)==sqf(n+1), print(n)))

(PARI) { n=0; s=0; for (m=1, 10^9, t=sumdiv(m + 1, d, if(issquarefree(d), d, 0)); if(s==t, write("b063964.txt", n++, " ", m); if (n==170, break)); s=t ) } [From Harry J. Smith, Sep 04 2009]

CROSSREFS

Cf. A048250.

Sequence in context: A195818 A101840 A061087 * A262721 A174952 A209898

Adjacent sequences:  A063961 A063962 A063963 * A063965 A063966 A063967

KEYWORD

easy,nonn

AUTHOR

Jason Earls (zevi_35711(AT)yahoo.com), Sep 04 2001

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified June 28 20:39 EDT 2017. Contains 288840 sequences.