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A345056 a(n) is the next larger number k > n for which A011772(k) = A011772(n), or n itself if no such larger number exists. 3
1, 6, 3, 14, 10, 6, 21, 20, 12, 10, 55, 18, 26, 28, 15, 62, 34, 36, 57, 24, 21, 33, 253, 30, 50, 39, 117, 28, 58, 40, 93, 72, 66, 68, 105, 36, 74, 95, 78, 60, 82, 70, 129, 48, 45, 69, 1081, 88, 56, 75, 153, 130, 106, 63, 55, 84, 171, 203, 1711, 120, 122, 124, 126, 254, 325, 66, 201, 136, 92, 210, 355, 96, 146, 111, 100, 114 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..76.

FORMULA

a(n) = n + A345057(n).

PROG

(PARI)

A011772(n) = { if(n==1, return(1)); my(f=factor(if(n%2, n, 2*n)), step=vecmax(vector(#f~, i, f[i, 1]^f[i, 2]))); forstep(m=step, 2*n, step, if(m*(m-1)/2%n==0, return(m-1)); if(m*(m+1)/2%n==0, return(m))); }; \\ From A011772

A345056(n) = { my(x=A011772(n), y=binomial(x+1, 2)); for(i=1+n, y, if(A011772(i)==x, return(i))); (n); };

CROSSREFS

Cf. A000217, A002024, A011772, A066561, A345057, A345058.

Sequence in context: A320038 A214498 A128756 * A049784 A341746 A097917

Adjacent sequences:  A345053 A345054 A345055 * A345057 A345058 A345059

KEYWORD

nonn

AUTHOR

Antti Karttunen, Jun 07 2021

STATUS

approved

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Last modified September 22 09:41 EDT 2021. Contains 347606 sequences. (Running on oeis4.)