A064125 Numbers k such that k and k+1 have the same sum of unitary divisors (A034448).

14, 44, 55, 152, 957, 1334, 1400, 1634, 1652, 2204, 2232, 2295, 2685, 3195, 3451, 3956, 4256, 5547, 7191, 8216, 8495, 8636, 8907, 9144, 9503, 9844, 10152, 11515, 17255, 18423, 19491, 20145, 20155, 27404, 27643, 30247, 33998, 38180, 41265

Offset

1,1

Links

Giovanni Resta, Table of n, a(n) for n = 1..10000 (first 800 terms from Harry J. Smith)

Prog

(PARI) usigma(n, s=1, fac, i)=fac=factor(n); for(i=1, matsize(fac)[1], s=s*(1+fac[i, 1]^fac[i, 2])); return(s); j=[]; for(n=1, 50000, if(usigma(n)==usigma(n+1), j=concat(j, n))); j
(PARI) usigma(n)= { local(f, s=1); f=factor(n); for(i=1, matsize(f)[1], s*=1 + f[i, 1]^f[i, 2]); return(s) }
{ n=0; s=0; for (m=1, 10^9, us=usigma(m+1); if(s==us, write("b064125.txt", n++, " ", m); if (n==800, break)); s=us ) } \\ Harry J. Smith, Sep 08 2009

Crossrefs

Sequence in context: A041380 A151990 A156166 * A089031 A265152 A033587

Adjacent sequences: A064122 A064123 A064124 * A064126 A064127 A064128

Keyword

easy,nonn

Author

Jason Earls, Sep 10 2001

Status

approved