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 A115426 Numbers k such that the concatenation of k with k+2 gives a square. 24
 7874, 8119, 69476962, 98010199, 108746354942, 449212110367, 544978035127, 870501316279, 998001001999, 1428394731903223, 1499870932756487, 1806498025502498, 1830668275445687, 1911470478658759, 2255786189655202 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Numbers k such that k concatenated with k+1 gives the product of two numbers which differ by 2. Numbers k such that k concatenated with k-2 gives the product of two numbers which differ by 4. Numbers k such that k concatenated with k-7 gives the product of two numbers which differ by 6. LINKS Table of n, a(n) for n=1..15. EXAMPLE 8119//8121 = 9011^2, where // denotes concatenation. 98010199//98010200 = 99000100 * 99000102. 98010199//98010197 = 99000099 * 99000103. CROSSREFS Cf. A030465, A102567, A115427, A115428, A115429, A115430, A115431, A115432, A115433, A115434, A115435, A115436, A115437. Cf. A116106, A116110, A116112, A116125, A116242. Cf. A116136, A116143, A116107, A116275, A116163, A116099, A116177, A116295. Sequence in context: A286208 A268583 A045292 * A206069 A237969 A256163 Adjacent sequences: A115423 A115424 A115425 * A115427 A115428 A115429 KEYWORD base,nonn AUTHOR Giovanni Resta, Jan 24 2006 EXTENSIONS Edited by N. J. A. Sloane, Apr 13 2007 STATUS approved

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Last modified September 27 01:46 EDT 2023. Contains 365669 sequences. (Running on oeis4.)