A137395 a(1)=1. a(n) = a(n-1) + (sum of the distinct primes that are <= n and don't divide a(n-1)).

1, 3, 5, 10, 13, 23, 40, 50, 60, 67, 95, 118, 157, 198, 223, 264, 306, 342, 395, 467, 544, 602, 693, 772, 870, 960, 1050, 1133, 1251, 1377, 1517, 1677, 1821, 1978, 2113, 2273, 2470, 2628, 2820, 3007, 3214, 3450, 3698, 3934, 4206, 4482, 4805, 5097, 5422, 5748

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

The primes <= 8 are 2,3,5,7. Of these, only 3 and 7 don't divide a(7)=40. So a(8) = a(7) + 3 + 7 = 50.

Maple

A137395 := proc(n) option remember ; local aprev, i, a, p; if n = 1 then RETURN(1) ; fi; aprev := A137395(n-1) ; a := aprev ; for i from 1 do p := ithprime(i) ; if p > n then break; fi ; if aprev mod p <> 0 then a := a+p ; fi ; od: a ; end: seq(A137395(n), n=1..100) ; # R. J. Mathar, May 23 2008

Mathematica

nxt[{n_, a_}]:=Module[{dpdd=Total[Select[Prime[Range[PrimePi[n+1]]], !Divisible[ a, #]&]]}, {n+1, a+dpdd}]; NestList[nxt, {1, 1}, 50][[All, 2]] (* Harvey P. Dale, Apr 28 2018 *)

Crossrefs

Sequence in context: A265282 A160792 A308759 * A001767 A360956 A273160

Adjacent sequences: A137392 A137393 A137394 * A137396 A137397 A137398

Keyword

nonn

Author

Leroy Quet, Apr 10 2008

Extensions

More terms from R. J. Mathar, May 23 2008

Status

approved