A387902 - OEIS

A387902

Index of A002313(n) in A005529.

1, 2, 4, 3, 9, 5, 6, 16, 8, 20, 24, 15, 7, 23, 11, 27, 31, 21, 56, 13, 57, 10, 76, 64, 46, 12, 58, 42, 37, 97, 18, 81, 105, 95, 30, 74, 82, 45, 14, 101, 22, 129, 49, 78, 33, 148, 168, 36, 84, 61, 17, 53, 88, 25, 136, 111, 106, 75, 40, 19, 94, 69, 250, 62, 28, 44, 225, 152, 226

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OFFSET

1,2

COMMENTS

Both A002313 and A005529 are lists of the primes which have -1 as a quadratic residue, but are ordered differently. The sequence {a(n)} is a permutation of the positive integers. It would be of interest if permutations obtained from other quadratic residues, such as 2 mod(p), although involving different primes, were abstractly related to this permutation.

LINKS

Table of n, a(n) for n=1..69.

EXAMPLE

a(122)=372 because the 122nd prime listed in A002313 is 1609, and the index of 1609 in A005529 is 372.

CROSSREFS

Sequence in context: A000463 A366260 A366946 * A358534 A137442 A350150

Adjacent sequences: A387899 A387900 A387901 * A387903 A387904 A387905

KEYWORD

nonn

AUTHOR

Richard Peterson, Sep 11 2025

STATUS

approved