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A175261 Each term is the smallest positive integer both coprime to all earlier terms of the sequence and with a different number of divisors than all earlier terms. (a(1)=1.) 0
1, 2, 9, 35, 1573, 7429, 707281, 1315609, 3397301, 12780049 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..10.

PROG

(PARI) isok(v, vd, nb, k) = {if (vecsearch(vd, numdiv(k)), return (0)); for (j=1, nb, if (gcd(k, v[j]) != 1, return (0)); ); 1; }

findk(v, nb) = {my(k = 1); my(vd = vecsort(vector(nb, j, numdiv(v[j])), , 8)); while (!isok(v, vd, nb, k), k++); k; }

lista(nn) = {va = vector(nn); print1(va[1] = 1, ", "); for (n=2, nn, k = findk(va, n-1); print1(va[n] = k, ", "); ); } \\ Michel Marcus, Feb 25 2016

CROSSREFS

Cf. A175231.

Sequence in context: A185034 A185234 A175231 * A086556 A192694 A192702

Adjacent sequences:  A175258 A175259 A175260 * A175262 A175263 A175264

KEYWORD

more,nonn

AUTHOR

Leroy Quet, Mar 16 2010

EXTENSIONS

a(6)-a(10) from Michel Marcus, Feb 25 2016

STATUS

approved

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Last modified February 23 23:15 EST 2018. Contains 299595 sequences. (Running on oeis4.)