A115896 Numbers k such that k + phi(k) is a palindrome.

1, 2, 3, 4, 5, 6, 17, 21, 61, 63, 71, 142, 157, 167, 183, 184, 190, 197, 201, 213, 215, 219, 237, 255, 263, 283, 284, 293, 305, 322, 325, 338, 359, 375, 379, 389, 395, 407, 412, 427, 445, 452, 458, 459, 460, 483, 535, 539, 549, 566, 568, 586, 595, 603, 941

Offset: 1

Author

Giovanni Resta, Feb 06 2006

Keywords

• nonn
• base

Examples

			183 + phi(183) = 183 + 120 = 303.
		

Links

• Robert Israel, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A115890, A115895, A115897.

Cf. A121048 (n+phi(n)).

Programs

Maple

ispali:= proc(n) local L; L:= convert(n,base,10); andmap(t -> L[t]=L[-t], [$1..nops(L)/2]) end proc:
select(t -> ispali(t+numtheory:-phi(t)), [$1..1000]); # Robert Israel, Sep 19 2022

Mathematica

nppQ[n_]:=Module[{idn=IntegerDigits[n+EulerPhi[n]]},idn==Reverse[idn]]; Select[Range[1000],nppQ] (* Harvey P. Dale, Aug 18 2013 *)

PARI

ispal(n) = my(d=digits(n)); d == Vecrev(d) \\ A002113
isok(k) = ispal(k+eulerphi(k)) \\ Alexandru Petrescu, Sep 19 2022