A346489 a(n) is the index of the smallest prime whose digits sum to n-th prime.

1, 2, 3, 4, 10, 19, 24, 46, 109, 430, 669, 3245, 6057, 7837, 33067, 77777, 476643, 601855, 3556550, 5216954, 15739663, 41146179, 189961757, 882206624, 3325059246, 15581005618, 23007498153, 37607875618

Offset

1,2

Links

Table of n, a(n) for n=1..28.

Formula

a(n) = A000720(A054750(n)).

a(n) = min {k : A007605(k) = prime(n)}.

Example

a(10) = 430 because prime(430) = 2999, 2 + 9 + 9 + 9 = 29 = prime(10) and this is the smallest such number.

Mathematica

Module[{nn=522*10^4, tbl}, tbl=Table[{n, Total[IntegerDigits[Prime[n]]]}, {n, nn}]; Table[SelectFirst[tbl, #[[2]]==Prime[n]&], {n, 20}]][[;; , 1]] (* The program generates the first 20 terms of the sequence. *) (* Harvey P. Dale, Feb 19 2023 *)

Crossrefs

Cf. A000040, A000720, A007605, A028834, A046704, A046864, A054750, A075177.

Sequence in context: A049891 A135432 A108364 * A145028 A306107 A229545

Adjacent sequences: A346486 A346487 A346488 * A346490 A346491 A346492

Keyword

nonn,base

Author

Ilya Gutkovskiy, Jul 19 2021

Status

approved