A108077 - OEIS

A108077

Largest prime p such that p-1 divides n.

2, 3, 2, 5, 2, 7, 2, 5, 2, 11, 2, 13, 2, 3, 2, 17, 2, 19, 2, 11, 2, 23, 2, 13, 2, 3, 2, 29, 2, 31, 2, 17, 2, 3, 2, 37, 2, 3, 2, 41, 2, 43, 2, 23, 2, 47, 2, 17, 2, 11, 2, 53, 2, 19, 2, 29, 2, 59, 2, 61, 2, 3, 2, 17, 2, 67, 2, 5, 2, 71, 2, 73, 2, 3, 2, 5, 2, 79, 2, 41, 2, 83, 2, 43

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OFFSET

1,1

LINKS

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

Antti Karttunen, Data supplement: n, a(n) computed for n = 1..100000

MAPLE

with(numtheory): for n from 1 to 110 do div:=divisors(n): A:=[seq(div[j]+1, j=1..tau(n))]: B:={}: for i from 1 to tau(n) do if isprime(A[i])=true then B:=B union {A[i]} else B:=B: fi: od: C:=convert(B, list): a[n]:=C[nops(C)] od: seq(a[n], n=1..110); # Emeric Deutsch, Aug 05 2005

PROG

(PARI) A108077(n) = fordiv(n, d, if(isprime(1+(n/d)), return(1+(n/d)))); \\ Antti Karttunen, Dec 19 2018

CROSSREFS

Largest term in row n of A108939.

Sequence in context: A079868 A280697 A088444 * A248737 A141310 A007389

Adjacent sequences: A108074 A108075 A108076 * A108078 A108079 A108080

KEYWORD

nonn,easy

AUTHOR

Philippe Deléham, Jul 20 2005

EXTENSIONS

More terms from Emeric Deutsch, Aug 05 2005

STATUS

approved