

A332073


The Silver Comma sequence: Differences of indices of prime terms gives back the sequence; lexicographically earliest such permutation of positive integers.


0



1, 2, 3, 4, 5, 6, 8, 7, 9, 10, 12, 11, 14, 15, 16, 18, 13, 20, 21, 22, 24, 25, 17, 26, 27, 28, 30, 32, 33, 34, 19, 35, 36, 38, 39, 40, 42, 23, 44, 45, 46, 48, 49, 50, 51, 52, 29, 54, 55, 56, 57, 58, 60, 62, 63, 64, 31, 65, 66, 68, 69, 70, 72, 74, 75, 76, 77, 78, 37, 80, 81, 82, 84, 85, 86, 87, 88, 90, 91, 41
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OFFSET

1,2


LINKS

Table of n, a(n) for n=1..80.
Eric Angelini, Yellow commas, pink, red, blue..., personal blog "Cinquante signes" on blogspot.com, May 17 2020


EXAMPLE

The prime terms are at indices 2, 3, 5, 8, 12, 17, 23, 31, 38, 47, 57, 69, 80, 94, ...; first differences give 1, 2, 3, 4, 5, 6, 8, 7, 9, 10, 12, 11, 14, ... = the sequence itself.


PROG

(PARI) upto(N)={local(U=[2]); my(a=Vec([1, 2], N), i=1, L=2, nxt(p)=while(#U>1 && U[2]==U[1]+1, U=U[^1]); my(t=U[1]); until(if(p, t=nextprime(t+1), !isprime(t+=1)) && !setsearch(U, t), ); U=setunion(U, [t]); t); for(n=3, N, a[n]=nxt(nL==a[i] && i++ && L=n)); a}


CROSSREFS

Cf. A197756 (the Yellow Comma sequence: count digits between odd terms).
Sequence in context: A127388 A307032 A273859 * A117332 A242704 A334111
Adjacent sequences: A332070 A332071 A332072 * A332074 A332075 A332076


KEYWORD

nonn


AUTHOR

Eric Angelini and M. F. Hasler, May 19 2020


STATUS

approved



