A137929 - OEIS

A137929

If n = the k-th prime power (including 1), then a(n) = the (k+1)th prime power. If n = the k-th positive integer that is not a prime power, then a(n) = the (k+1)th positive integer that is not a prime power.

2, 3, 4, 5, 7, 10, 8, 9, 11, 12, 13, 14, 16, 15, 18, 17, 19, 20, 23, 21, 22, 24, 25, 26, 27, 28, 29, 30, 31, 33, 32, 37, 34, 35, 36, 38, 41, 39, 40, 42, 43, 44, 47, 45, 46, 48, 49, 50, 53, 51, 52, 54, 59, 55, 56, 57, 58, 60, 61, 62, 64, 63, 65, 67, 66, 68, 71

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OFFSET

1,1

COMMENTS

This is a permutation of the positive integers excluding 1 and 6.

LINKS

Table of n, a(n) for n=1..67.

PROG

(PARI) ispp(n) = (n==1) || isprimepower(n);

lista(nn) = {vn = vector(nn, i, i); vpp = select(n->ispp(n), vn); vnpp = select(n->(!ispp(n)), vn); vr = vector(nn); for (i=1, #vpp-1, vr[vpp[i]] = vpp[i+1]; ); for (i=1, #vnpp-1, vr[vnpp[i]] = vnpp[i+1]; ); for (i=1, nn, if (vr[i], print1(vr[i], ", "), return()); ); } \\ Michel Marcus, Feb 10 2014

CROSSREFS

Cf. A000961, A024619.

Sequence in context: A272072 A118463 A214652 * A094617 A254318 A047502

Adjacent sequences: A137926 A137927 A137928 * A137930 A137931 A137932

KEYWORD

nonn

AUTHOR

Leroy Quet, Apr 30 2008

EXTENSIONS

More terms from Michel Marcus, Feb 10 2014

STATUS

approved