

A298990


Least number m such that A035026(m) = n.


1



1, 2, 4, 5, 8, 11, 12, 17, 18, 37, 24, 53, 30, 89, 39, 71, 42, 101, 45, 179, 57, 137, 72, 193, 60, 233, 84, 257, 90, 251, 117, 401, 123, 311, 144, 373, 120, 347, 105, 457, 162, 661, 150, 479, 180, 547, 237, 599, 165, 617, 264, 641, 288, 683, 195, 907, 231, 881
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OFFSET

0,2


COMMENTS

The upper branch visible in the scatterplot of the first terms corresponds to oddindexed terms.  Rémy Sigrist, Jan 31 2018


LINKS

Rémy Sigrist, Table of n, a(n) for n = 0..10000
Rémy Sigrist, C++ program for A298990


EXAMPLE

2* 2 = 2 + 2, so a(1) = 2.
2* 4 = 3 + 5 = 5 + 3, so a(2) = 4.
2* 5 = 3 + 7 = 5 + 5 = 7 + 3, so a(3) = 5.
2* 8 = 3 + 13 = 5 + 11 = 11 + 5 = 13 + 3, so a(4) = 8.
2*11 = 3 + 19 = 5 + 17 = 11 + 11 = 17 + 5 = 19 + 3, so a(5) = 11.


PROG

(C++) See Links section.
(PARI) nb(n) = sum(i=1, 2*n1, isprime(i) && isprime(2*ni));
a(n) = {my(k=1); while (nb(k) != n, k++); k; } \\ Michel Marcus, Jan 31 2018


CROSSREFS

Cf. A035026.
Sequence in context: A174803 A282434 A105659 * A191169 A191122 A191338
Adjacent sequences: A298987 A298988 A298989 * A298991 A298992 A298993


KEYWORD

nonn,changed


AUTHOR

Seiichi Manyama, Jan 31 2018


STATUS

approved



