A066219 Numbers n such that |phi(n+1)-phi(n)| = |d(n+1)-d(n)|, where phi is Euler's totient function and d(n) = number of divisors of n.

5, 7, 45, 104, 105, 345, 1754, 3255, 16215, 17534, 22935, 67431, 70634, 93074, 983775, 1025504, 1156701, 2200694, 2619705, 2745765, 3365438, 4163355, 4447064, 4695704, 6372794, 7838265, 9718904, 11903775, 23992215, 26879684, 29357475, 37239735, 40588485

Offset

1,1

Links

Table of n, a(n) for n=1..33.

Example

|phi(6)-phi(5)| = |2-4| = |d(6)-d(5)| = |4-2|

Prog

(PARI) ph1=1; d1=1; for(n=1, 40588485, ph2=eulerphi(n+1); d2=numdiv(n+1); if(abs(ph2-ph1)==abs(d2-d1), print1(n ", ")); ph1=ph2; d1=d2) /* Donovan Johnson, Oct 19 2012 */

Crossrefs

Sequence in context: A213175 A265786 A090520 * A278618 A174267 A306649

Adjacent sequences: A066216 A066217 A066218 * A066220 A066221 A066222

Keyword

nonn

Author

Joseph L. Pe, Dec 17 2001

Extensions

a(7)-a(33) from Donovan Johnson, Oct 19 2012

Status

approved