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A067249 Digits of sigma(n) end in phi(n). 1
1, 6, 84, 112, 141, 294, 1188, 1320, 2508, 4584, 5406, 8850, 14270, 17416, 23320, 31152, 79035, 117576, 125576, 132066, 149877, 160664, 162514, 164024, 167970, 170980, 177744, 184584, 223286, 1119636, 1124592, 1216644, 1481800, 1566920, 1626716 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

There are only 46 terms up to 10 million. - Harvey P. Dale, Oct 04 2012

LINKS

Harvey P. Dale and Donovan Johnson, Table of n, a(n) for n = 1..150 (first 46 terms from Harvey P. Dale)

EXAMPLE

sigma(79035) = 138240 ends in phi(79035) = 38240, so 79035 is a term of the sequence.

MATHEMATICA

(*returns true if a ends with b, false o.w.*) f[a_, b_] := Module[{c, d, e, g, h, i, r}, r = False; c = ToString[a]; d = ToString[b]; e = StringLength[c]; g = StringPosition[c, d]; h = Length[g]; If[h > 0, i = g[[h]]; If[i[[2]] == e, r = True]]; r]; Select[Range[10^5], f[DivisorSigma[1, # ], EulerPhi[ # ]] & ]

dsepQ[n_]:=Module[{ep=EulerPhi[n]}, Mod[DivisorSigma[1, n], 10^ IntegerLength[ ep]]==ep]; Select[Range[250000], dsepQ] (* Harvey P. Dale, Oct 04 2012 *)

CROSSREFS

Sequence in context: A186659 A196256 A230491 * A288321 A155191 A211171

Adjacent sequences:  A067246 A067247 A067248 * A067250 A067251 A067252

KEYWORD

base,nonn

AUTHOR

Joseph L. Pe, Feb 20 2002

EXTENSIONS

More terms from Vladeta Jovovic, Feb 22 2002

STATUS

approved

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Last modified November 15 01:25 EST 2019. Contains 329143 sequences. (Running on oeis4.)