OFFSET
1,1
COMMENTS
a(15), if it exists, is at least 10^8. The sequence then continues 31, 239, 41, 227, 43, 25, 339, 683, 71, 31, 151, 43, 67, 2897, 89, 59, 61, 81, 97, 35, 131, 110039, 461, 69, 103, 31, 123, 87981, 1941, 53, 197, 311, 213, 41, 161, 141, 187, 67, 143, 167, 161, 89, 353, 479, 339, 124809, 339, 61, 143, 79, 233, 6723723, 313, 724747, 97, 113, 211, 863, 281, 131, 343, 121, 569, 59217, 127, 127, 309, 61, 271, 103, 1329, 359, 229, 79, 299, 89, 911, 264263, 575, 14627, 281, 139, 203, 267, 211, ..., . - Robert G. Wilson v, Jun 09 2009
MATHEMATICA
a[n_] := For[m=1, True, m++, p=EulerPhi[m]; If[DivisorSigma[1, n+p]==DivisorSigma[1, p], Return[m]]]
f[n_] := Block[{k = 1}, While[ DivisorSigma[1, n + EulerPhi@k] != DivisorSigma[1, EulerPhi@k], k++ ]; k] (* Robert G. Wilson v, Jun 09 2009 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Jason Earls, May 27 2002
EXTENSIONS
Edited by Dean Hickerson, Jun 02 2002
I extended the search from 7*10^7 to 10^8 Robert G. Wilson v, Jun 09 2009
STATUS
approved