A074495 a(n) = the first prime > sigma(n).

2, 5, 5, 11, 7, 13, 11, 17, 17, 19, 13, 29, 17, 29, 29, 37, 19, 41, 23, 43, 37, 37, 29, 61, 37, 43, 41, 59, 31, 73, 37, 67, 53, 59, 53, 97, 41, 61, 59, 97, 43, 97, 47, 89, 79, 73, 53, 127, 59, 97, 73, 101, 59, 127, 73, 127, 83, 97, 61, 173, 67, 97, 107, 131, 89, 149, 71, 127, 97, 149, 73, 197, 79, 127, 127, 149, 97, 173, 83

Offset

1,1

Links

Antti Karttunen, Table of n, a(n) for n = 1..16384

Index entries for sequences related to sigma(n)

Formula

From Antti Karttunen, Nov 17 2017: (Start)

a(n) = A151800(A000203(n)).

a(n) >= A067792(n).

(End)

Example

The least prime > sigma(6) = 12 is 13, so a(6) = 13.
The least prime > sigma(7) =  8 is 11, so a(7) = 11.

Mathematica

p[n_] := Module[{r, i}, r = 2; i = 1; While[r <= n, i = i + 1; r = Prime[i]]; r]; Table[p[DivisorSigma[1, n]], {n, 1, 40}]

Prog

(PARI) A074495(n) = nextprime(1+sigma(n)); \\ Antti Karttunen, Nov 16 2017

Crossrefs

Cf. A000203, A151800, A067792, A072918.

Sequence in context: A238655 A132295 A086651 * A081467 A194119 A084721

Adjacent sequences: A074492 A074493 A074494 * A074496 A074497 A074498

Keyword

easy,nonn

Author

Joseph L. Pe, Sep 26 2002

Extensions

More terms from Antti Karttunen, Nov 16 2017

Status

approved