A002396 Inverse of reduced totient function.

1, 3, 5, 7, 32, 11, 13, 17, 19, 25, 23, 224, 29, 31, 128, 37, 41, 43, 115, 47, 119, 53, 81, 928, 59, 61, 256, 67, 71, 73, 79, 187, 83, 203, 89, 209, 235, 97, 101, 103, 1696, 107, 109, 121, 113, 295, 287, 127, 512, 131, 299, 137, 139, 319, 323, 149, 151, 157, 1408

Offset: 1

Author

N. J. A. Sloane

Keywords

• nonn
• nice
• easy

Comments

The position of the first i = 1, 2, 3, 4, 5, 6 .... in A002322 is 1, 3, 0, 5, 0, 7, 0, 32, 0, 11, 0, 13, 0, 0, 0, 17, 0, 19, 0, 25 with zeros if i is absent. Deleting the zeros (keeping A002202) defines this sequence. - R. J. Mathar, Jul 22 2025

References

• D. H. Lehmer, Guide to Tables in the Theory of Numbers. Bulletin No. 105, National Research Council, Washington, DC, 1941, pp. 7-10.
• N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
• N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Links

• T. D. Noe, Table of n, a(n) for n = 1..1000
• C. Moreau, Sur quelques théorèmes d'arithmétique, Nouvelles Annales de Mathématiques, 17 (1898), 293-307.

Programs

Mathematica

max = 1000; Clear[a]; a[n_] := 100*n; a[2432] = 623104 (* given by T. D. Noe *); For[m = 0; n = 1, m <= max, n = If[n == 1, 2, n + 2], For[k = n, k <= a[n], k++, If[CarmichaelLambda[k] == n, m++; Print[{n, m, k}]; a[m] = k; Break[]]]]; Table[a[n], {n, 1, max}] (* Jean-François Alcover, Jan 15 2015 *)

Extensions

More terms from Brent Lehman (mailbjl(AT)yahoo.com), Apr 26 2005