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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. 0
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified July 12 12:18 EDT 2020. Contains 335661 sequences. (Running on oeis4.)